Insights from Technical Analysis on a Group of Paintings by Gerrit Dou in the Leiden Collection

Gerrit Dou,  Scholar Sharpening a Quill, ca. 1630–35, The Leiden Collection, New York

Over the past four years an inquiry has been conducted into the painting methods and materials employed by Gerrit Dou on a group of thirteen paintings in the Leiden Collection, New York, that spans the career of the artist. The study incorporates the results of diagnostic imaging by infrared techniques and X-radiography, analysis of selective pigment samples, dendrochronology of the support panels, and microscopic examination of Dou’s paint handling and sequences of application. The study has brought to light numerous revisions by the artist in developing these compositions, some of which shed light on more fundamental issues of meaning in the depictions.

DOI: 10.5092/jhna.2014.6.1.3

Appendix

Instrumental Methods

The technical study that underpins this essay may be loosely divided into two categories: examination methods and analytical methods. Technologically based examination methods included the use of magnification aids for visual examination, such as low magnification stereobinocular microscopy, several forms of infrared imaging, ultraviolet fluorescence examination, and X-ray radiography (contributors to these phases include conservators Shawn Digney-Peer, Annette Rupprecht, and Nancy Krieg, and radiographer Peter Branch, as noted). In the case of infrared examination, the terminology of the field has not kept pace with instrumental developments. The retention of terms based upon distinctions in the capabilities of film and vidicon IR devices is problematic and counterproductive with the advent of digital photography based on CCD detectors that extend the range of SLR cameras into the near infrared. It is more essential than ever to specifically identify the range of the IR spectrum accessed by the equipment in use. For these reasons we prefer the use of “infrared imaging” supplemented by appropriate details, in preference to terms such as “infrared photography” and “infrared reflectography” or “IRR.”

Instrumental analytical methods for identification of the materials of the paintings were carried out by one of the authors (Twilley) and included the preparation of cross sections for optical examination at high magnification in reflected light, by ultraviolet fluorescence microscopy, and by Scanning Electron Microscopy (SEM). Elemental analyses were carried out on both cross sections and paint fracture fragments in the course of SEM examination using energy-dispersive X-ray spectrometry. In a few cases, cross sections were subsequently reduced to thin sections of 10 microns thickness for examination in transmitted light using the polarizing microscope. Pigment dispersions were examined as slide mounts using the polarizing microscope, whereby optical properties of individual pigment particles may be tested for characteristics such as refractive index, birefringence, pleochroism, cleavage, and crystal habit. Raman microspectroscopy was used for identification of pigments as loose particles, in slide mounts and in cross sections, as necessary. Exceptionally, we employed darkfield metallographic microscopy at magnifications up to 1,000x directly on the painting or rear support surface (GD-102 and GD-111, respectively).

Examination Methods

Nikon D700 UV/IR modified CCD camera with longpass filters at 780, 850, and 1000 nanometers (Rupprecht)

FLIR Alpha NIR InGaAs camera with bandpass filter, effective range of 1500-1680 nm (Digney-Peer)

Nikon 995 CCD camera, modified for IR use, with bandpass filters as follows, all used for normal and macro-scale imaging (Twilley):

785 nm, fwhm=20 nm (Omega);

815 nm, fwhm=90 nm (Omega);

880 nm, fwhm=10 nm (Omega);

905 nm, fwhm=35 nm (Omega); and

1000 nm, fwhm=70 nm (ThermoCorion).

Nikon 995 CCD camera, modified for IR use, with 875 nm longpass filter (Omega), for IR documentation of microscopic features (effective wavelength 875-1050 nm) using the stereobinocluar microscope (Twilley)

Hamamatsu infrared vidicon camera C2741-03 with one of the following filters, each used with iterative frame averaging of 128 frames. (Twilley):

broadband 1100-1600 nm (Omega);

broadband 1230-1580 nm (Spectrogon);

broadband 1485-1665 nm (Omega);

1500 nm longpass filter (Omega); or

1600 nm longpass filter (CVI Laser Corp.)

X-ray radiography was carried out as part of a larger radiography campaign on a wider group of paintings in the Leiden Collection in 2009 by Peter Branch of Branch Radiographic Laboratories in Cranford, New Jersey. Digital radiography was employed, due to constraints imposed by the gallery premises. An Xscan CR unit with 14×17 inch plate was used with an air-cooled X-ray tube. Exposure conditions were optimized for the needs of individual paintings. Typical exposures required were 35-40kV at 4.5mAsec. Images were extracted into QPCXSCAN32 (iCRco, Inc.,Torrance, CA) in the DICOND format at 254 dpi, 16 bit grayscale, and exported for further processing in Photoshop.

Analytical Method (Twilley)

Cross sections were embedded under vacuum in low molecular weight epoxy cured with a cycloaliphatic amine hardener (Hxtal) at 60 degrees Celsius. Grinding and polishing were carried out using successive grades of silicon carbide abrasive paper through 600 mesh, terminating with 1 micron aluminum oxide suspended in aliphatic hydrocarbon fluid on napless nylon fabric.

Scanning electron microscope: Leo1550, utilizing a Schottky FEI source and both secondary and backscatter electron imaging modes. Fracture sections and particulate samples were adhered to conductive carbon tape. Both fracture sections and embedded cross sections were rendered conductive by coating with vacuum-evaporated carbon prior to examination. Beam accelerating voltage was typically 20kV for backscatter imaging. Secondary electron imaging of low-density structures was conducted at 12kV when necessary.

X-ray spectrometer: Edax energy dispersive Si(Li) drifted detector. Spectra were collected and processed via an iXRF Corp. interface and Iridium software.

Raman spectroscopy: Chromex Senturion dispersive Raman spectrometer, 785 nm excitation, spectra were collected in Stokes mode over the range of 180-1680 cm-1, with resolution of 4 cm-1

Polarized light microscopy: Nikon Microphot SA pol, using 1x, 4x, 10x, 20x, 40x, 60x and 100x planapochromat objectives.

Ultraviolet fluorescence microscopy: Nikon Microphot FXA, using 4x, 10x, 20x, and 40x planapofluor objectives with a Nikon UV20 filter block (UV excitation, full visible spectrum emission).

Metallographic (darkfield reflected light) microscopy: Olympus modular wafer-inspection microscope using brightfield/darkfield, infinity-corrected 5x, 20x, 50x, and 100x LMPlanfl objectives.

The dendrochronological analyses were performed by both UK-based dendrochronologist Ian Tyers, and Hamburg-based dendrochronologist Peter Klein.

Unless otherwise noted, all observations and conclusions are those of the authors.

Acknowledgements

In commemoration of Gerrit Dou’s four hundredth birthday, 2013 marks the year in which the groundwork for this article was prepared as a result of presentations given on various related topics by the authors at the following conferences: the CODART ZESTIEN Congress in Vienna, April 21–23, 2013; Rembrandt and His Circle: An International Colloquium, organized by Queen’s University for the Bader International Study Center at Herstmonceux Castle, July 18–21, 2013; and Painting Techniques: An International Symposium at the Rijksmuseum, Amsterdam, September 18–20, 2013. The authors wish to thank Arthur K. Wheelock Jr. and the two anonymous readers of the manuscript for their valuable comments on earlier versions of this article.

Gerrit Dou,  Scholar Sharpening a Quill,  ca. 1630–35,  The Leiden Collection, New York
Fig. 1a Gerrit Dou, Scholar Sharpening a Quill, ca. 1630–35, oil on panel, 25 x 20.5 cm, oval, signed, center right, under quill, “GD”(GD in ligature). The Leiden Collection, New York, GD-104 [comparison viewer]
Gerrit Dou,  Scholar Sharpening a Quill, verso,  ca. 1630–35,  The Leiden Collection, New York
Fig. 1b Gerrit Dou, Scholar Sharpening a Quill, verso,  ca. 1630–35,  The Leiden Collection, New York [comparison viewer]
Gerrit Dou,  Scholar Interrupted at His Writing,  ca. 1635,  The Leiden Collection, New York
Fig. 2a Gerrit Dou, Scholar Interrupted at His Writing, ca. 1635, oil on panel, 24.5 x 20 cm, oval, signed, on a piece of paper protruding from the book, “GDov” (GD in ligature). The Leiden Collection, New York, GD-102 [comparison viewer]
Gerrit Dou,  Scholar Interrupted at His Writing, verso,  ca. 1635,  The Leiden Collection, New York
Fig. 2b Gerrit Dou, Scholar Interrupted at His Writing, verso,  ca. 1635,  The Leiden Collection, New York [comparison viewer]
Gerrit Dou,  Portrait of a Young Man with a Hat,  ca. 1635,  The Leiden Collection, New York
Fig. 3a Gerrit Dou, Portrait of a Young Man with a Hat, ca. 1635, oil on panel, 38 x30.5 cm. The Leiden Collection, New York, GD-100 [comparison viewer]
Gerrit Dou,  Portrait of a Young Man with a Hat, verso,  ca. 1635,  The Leiden Collection, New York
Fig. 3b Gerrit Dou, Portrait of a Young Man with a Hat, verso,  ca. 1635,  The Leiden Collection, New York [comparison viewer]
Gerrit Dou,  Portrait of a Lady in Profile,  ca. 1635–40,  The Leiden Collection, New York
Fig. 4a Gerrit Dou, Portrait of a Lady in Profile, ca. 1635–40, oil on panel, oval inlaid into a rectangular panel, 13.3 x 11.3 cm, signed, left center, “GDou” (GD in ligature). The Leiden Collection, New York, GD-110 [comparison viewer]
Gerrit Dou,  Portrait of a Lady in Profile, verso,  ca. 1635–40,  The Leiden Collection, New York
Fig. 4b Gerrit Dou, Portrait of a Lady in Profile, verso,  ca. 1635–40,  The Leiden Collection, New York [comparison viewer]
Gerrit Dou,  Portrait of a Gentleman with a Walking Stick,  ca. 1645,  The Leiden Collection, New York
Fig. 5a Gerrit Dou, Portrait of a Gentleman with a Walking Stick, ca. 1645, oil on panel, 49.2 x 39.7 cm, signed, right, “GDou”(GD in ligature). The Leiden Collection, New York, GD-113 [comparison viewer]
Gerrit Dou,  Portrait of a Gentleman with a Walking Stick, verso, ca. 1645, The Leiden Collection, New York
Fig. 5b Gerrit Dou, Portrait of a Gentleman with a Walking Stick, verso,  ca. 1645,  The Leiden Collection, New York [comparison viewer]
Gerrit Dou,  Portrait of a Lady with a Music Book,  ca. 1640–44,  The Leiden Collection, New York
Fig. 6a Gerrit Dou, Portrait of a Lady with a Music Book, ca. 1640–44, oil on panel, 27.1 x 19.8 cm, signed, on the book, “GDou”(GD in ligature). The Leiden Collection, New York, GD-116 [comparison viewer]
Gerrit Dou,  Portrait of a Lady with a Music Book, verso,  ca. 1640–44,  The Leiden Collection, New York
Fig. 6b Gerrit Dou, Portrait of a Lady with a Music Book, verso,  ca. 1640–44,  The Leiden Collection, New York [comparison viewer]
Gerrit Dou,  Cat Crouching on the Ledge of an Artist’s Atel, 1657,  The Leiden Collection, New York
Fig. 7a Gerrit Dou, Cat Crouching on the Ledge of an Artist’s Atelier, 1657, oil on panel, 34 x 26.7 cm, signed and dated, on the ledge,“GDou 1657”(GD in ligature). The Leiden Collection, New York, GD-108 [comparison viewer]
Gerrit Dou, Cat Crouching on the Ledge of an Artist’s Atelier, verso, 1657, The Leiden Collection, New York
Fig. 7b Gerrit Dou, Cat Crouching on the Ledge of an Artist’s Atelier, verso, 1657,  The Leiden Collection, New York [comparison viewer]
Gerrit Dou,  Portrait of Dirck van Beresteyn,  ca. 1652,  The Leiden Collection, New York
Fig. 8a Gerrit Dou, Portrait of Dirck van Beresteyn, ca. 1652, oil on silver-copper alloy support, oval, 10 x 8 cm, signed, upper right, “GDou”(GD in ligature). The Leiden Collection, New York, GD-111 [comparison viewer]
Gerrit Dou,  Portrait of Dirck van Beresteyn, verso,  ca. 1652,  The Leiden Collection, New York
Fig. 8b Gerrit Dou, Portrait of Dirck van Beresteyn, verso,  ca. 1652,  The Leiden Collection, New York [comparison viewer]
Gerrit Dou,  Young Woman Holding a Parrot,  ca. 1660–65,  The Leiden Collection, New York
Fig. 9a Gerrit Dou, Young Woman Holding a Parrot, ca. 1660–65, oil on panel, 24.8 x18.6 cm. The Leiden Collection, New York, GD-105 [comparison viewer]
Gerrit Dou,  Young Woman Holding a Parrot, verso,  ca. 1660–65,  The Leiden Collection, New York
Fig. 9b Gerrit Dou, Young Woman Holding a Parrot, verso,  ca. 1660–65,  The Leiden Collection, New York [comparison viewer]
Gerrit Dou,  Goat in a Landscape,  ca. 1660–65,  The Leiden Collection, New York
Fig. 10a Gerrit Dou, Goat in a Landscape, ca. 1660–65, oil on panel, 19.5 x24.9 cm, signed, lower center, “GDou” (GD in ligature). The Leiden Collection, New York, GD-114 [comparison viewer]
Gerrit Dou,  Goat in a Landscape, verso,  ca. 1660–65,  The Leiden Collection, New York
Fig. 10b Gerrit Dou, Goat in a Landscape, verso,  ca. 1660–65,  The Leiden Collection, New York [comparison viewer]
Gerrit Dou,  Hermit Praying,  ca. 1665–70,  The Leiden Collection, New York
Fig. 11a Gerrit Dou, Hermit Praying, ca. 1665–70, oil on panel, 18 x 12.9 cm, signed, center right, “GD”(GD in ligature). The Leiden Collection, New York, GD-107 [comparison viewer]
Gerrit Dou,  Hermit Praying, verso,  ca. 1665–70,  The Leiden Collection, New York
Fig. 11b Gerrit Dou, Hermit Praying, verso,  ca. 1665–70,  The Leiden Collection, New York [comparison viewer]
Gerrit Dou,  Old Woman at a Niche by Candlelight, 1671,  The Leiden Collection, New York
Fig. 12a Gerrit Dou, Old Woman at a Niche by Candlelight, 1671, oil on panel, 26.7 x20.8 cm, signed, bottom center, “GDovAnno 1671”(GD in ligature). The Leiden Collection, New York, GD-103 [comparison viewer]
Gerrit Dou,  Old Woman at a Niche by Candlelight, verso, 1671,  The Leiden Collection, New York
Fig. 12b Gerrit Dou, Old Woman at a Niche by Candlelight, verso, 1671,  The Leiden Collection, New York [comparison viewer]
Gerrit Dou,  Herring Seller and a Boy,  ca. 1664,  The Leiden Collection, New York
Fig. 13a Gerrit Dou, Herring Seller and a Boy, ca. 1664, oil on panel, 42.3 x 33.3 cm, signed, bottom center, “GDou”(GD in ligature). The Leiden Collection, New York, GD-106 [comparison viewer]
Gerrit Dou,  Herring Seller and a Boy, verso,  ca. 1664,  The Leiden Collection, New York
Fig. 13b Gerrit Dou, Herring Seller and a Boy, verso,  ca. 1664,  The Leiden Collection, New York [comparison viewer]
Detail of the cloak of the scholar’s proper rig,
Fig. 14 Detail of the cloak of the scholar’s proper right shoulder of Scholar Interrupted at His Writing showing losses that reveal a rust-colored sketch over a light-colored ground and primuersel, field of view: 2.75mm (photomicrograph: John Twilley) [comparison viewer]
Infrared image detail of Scholar Sharpening a Qu,
Fig. 15 Infrared image detail of Scholar Sharpening a Quill showing line underdrawings of the book and hourglass, together with a broader-brushed sketch at the top rim of the book. InGaAs camera using 1500-1680nm filter (image: Shawn Digney-Peer) [comparison viewer]
Infrared image detail of Scholar Interrupted at ,
Fig. 16 Infrared image detail of Scholar Interrupted at His Writing showing underdrawing and modeling around birdcage at the upper center. InGaAs camera using 1500-1680nm filter (image: Shawn Digney-Peer) [comparison viewer]
Detail of Scholar Interrupted at His Writing sh,
Fig. 17a Detail of Scholar Interrupted at His Writing showing visual detail of ear with faint sketch lines, field of view: 11mm (photomicrograph: John Twilley) [comparison viewer]
Infrared image detail of the face, 875-1100nm fil,
Fig. 17b Detail of Scholar Interrupted at His Writing showing infrared image detail of the face, 875-1100nm filter (photomicrograph: John Twilley) [comparison viewer]
Infrared image of Portrait of a Lady with a Musi,
Fig. 18 Infrared image of Portrait of a Lady with a Music Book showing delicate line drawing around the books, as well as vigorous undermodeling of the woman’s outer gown, in the dead coloring phase. InGaAs camera using 1500-1680nm filter (image: Shawn Digney-Peer) [comparison viewer]
Infrared image detail of Portrait of a Lady with,
Fig. 19 Infrared image detail of Portrait of a Lady with a Music Book showing the line underdrawing of the book on the woman’s lap. InGaAs camera using 1500-1680nm filter (image: Shawn Digney-Peer) [comparison viewer]
Infrared image detail of Portrait of a Lady with,
Fig. 20 Infrared image detail of Portrait of a Lady with a Music Book showing the line underdrawings of the books on the table at the far right. In GaAs camera using 1500-1680nm filter (image: Shawn Digney-Peer) [comparison viewer]
Infrared image detail of Hermit Praying showing,
Fig. 21 Infrared image detail of Hermit Praying showing underdrawing of the hands, 800-900nm filter (photograph: John Twilley) [comparison viewer]
Infrared image of Hermit Praying showing vigoro,
Fig. 22 Infrared image of Hermit Praying showing vigorous undermodeling in the cloak and changes along both shoulders, 950-1000nm filter (image: John Twilley) [comparison viewer]
Infrared image of Portrait of a Gentleman with a,
Fig. 23a Infrared image of Portrait of a Gentleman with a Walking Stick showing initial sketch of arched doorway in the background and column with base on the left. InGaAs camera using 1500-1680nm filter (image: Shawn Digney-Peer) [comparison viewer]
Portrait of a Gentleman with a Walking Stick
Fig. 23b Gerrit Dou, Portrait of a Gentleman with a Walking Stick, ca. 1645, oil on panel, 49.2 x 39.7 cm, signed, right, “GDou” (GD in ligature). The Leiden Collection, New York, GD-113 [comparison viewer]
Infrared image detail of Portrait of a Gentleman,
Fig. 24a Infrared image detail of Portrait of a Gentleman with a Walking Stick showing changes in the collar, lapel, or breastplate during the preparatory stage, 1000-1050nm filter (image: Annette Rupprecht) [comparison viewer]
Detail of Portrait of a Gentleman with a Walking Stick
Fig. 24b Gerrit Dou, Portrait of a Gentleman with a Walking Stick, detail, ca. 1645, oil on panel, 49.2 x 39.7 cm, signed, right, “GDou” (GD in ligature). The Leiden Collection, New York, GD-113 [comparison viewer]
Infrared image of Scholar Interrupted at His Wri,
Fig. 25 Infrared image of Scholar Interrupted at His Writing showing broad brushwork in the scholar’s garment and along the front of the table. InGaAs camera using 1500-1680nm filter (image:ShawnDigney-Peer) [comparison viewer]
Infrared image of Scholar Sharpening a Quill sh,
Fig. 26 Infrared image of Scholar Sharpening a Quill showing brushed sketch work of scarf around scholar’s neck and original position of the inkwell. InGaAs camera using 1500-1680nm filter (image: Shawn Digney-Peer) [comparison viewer]
Infrared image detail of Scholar Sharpening a Qu,
Fig. 27a Infrared image detail of Scholar Sharpening a Quill showing the brush sketch in the scarf around the scholar’s neck and the dead coloring around the figure’s proper left hand knuckles. InGaAs camera using 1500-1680nm filter (image: Shawn Digney-Peer) [comparison viewer]
Detail of Scholar Sharpening a Quill
Fig. 27b Gerrit Dou, Scholar Sharpening a Quill, detail, ca. 1630–35, oil on panel, 25 x 20.5 cm, oval, signed, center right, under quill, “GD”(GD in ligature). The Leiden Collection, New York, GD-104 [comparison viewer]
Sample from the cloak of Scholar Sharpening a Qu,
Fig. 28a Sample from the cloak of Scholar Sharpening a Quill showing the violet-brown dead color and upper violet lake layer (a) Cross section in reflected light (the top layer is retained only at the left end), 200x (photomicrograph: John Twilley) [comparison viewer]
Sample from the cloak of Scholar Sharpening a Qu,
Fig. 28b Sample from the cloak of Scholar Sharpening a Quill showing the violet-brown dead color and upper violet lake layer, UV autofluorescence differentiating the two layers, 200x (photomicrograph: John Twilley) [comparison viewer]
Sample from the cloak of Scholar Sharpening a Qu,
Fig. 28c Sample from the cloak of Scholar Sharpening a Quill showing the violet-brown dead color and upper violet lake layer, partially dispersed pigments from both layers showing particles of lake from the top layer and iron earth pigment with Kassel earth from the dead coloring, transmitted light with partially crossed polars, 400x (photomicrograph: John Twilley) [comparison viewer]
Infrared image of Old Woman at a Niche by Candle,
Fig. 29 Infrared image of Old Woman at a Niche by Candlelight showing broadly brushed sketch work in the initial design phase. InGaAs camera using1500-1680nm filter (image: Shawn Digney-Peer) [comparison viewer]
Infrared image of Herring Seller and a Boy, 100,
Fig. 30 Infrared image of Herring Seller and a Boy, 1000-1050nm filter (image: Annette Rupprecht) [comparison viewer]
Infrared image of Young Woman Holding a Parrot, 1000-1050nm filter (image: Annette Rupprecht)
Fig. 31 Infrared image of Young Woman Holding a Parrot, 1000-1050nm filter (image: Annette Rupprecht) [comparison viewer]
Detail of Portrait of Dirck van Beresteyn showi,
Fig. 32 Detail of Portrait of Dirck van Beresteyn showing the fine craquelure in the blue background near the mid-left edge, field of view: 6mm (photomicrograph: John Twilley) [comparison viewer]
Dispersed pigments from Portrait of Dirck van Be,
Fig. 33 Dispersed pigments from Portrait of Dirck van Beresteyn showing dark gray paint containing lead white, boneblack, well-preserved smalt, and isotropic hydrated iron oxide (goethite), transmitted light with partially crossed polars, 400x (photomicrograph: John Twilley) [comparison viewer]
Smalt grainfrom the blue background of Portrait ,
Fig. 34a Smalt grain from the blue background of Portrait of Dirck van Beresteyn (with adhering lead white particles), back scatter electron image, 4,720x (electron micrograph: John Twilley) [comparison viewer]
Elemental composition obtained by X-ray spectrome,
Fig. 34b Elemental composition obtained by X-ray spectrometry during SEM observation. Cobalt in a potash-silica glass is responsible for its blue color. Arsenic detected here is a typical contaminant in cobalt ores used for the coloring of smalt (electron micrograph: John Twilley) [comparison viewer]
Detail of Scholar Interrupted at His Writing sh,
Fig. 35 Detail of Scholar Interrupted at His Writing showing the scarf on the tablecloth emerging from beneath the book where a fine crack disclosed a series of blue layers beneath, field of view: 3.6mm (photomicrograph: John Twilley) [comparison viewer]
Cross section from Scholar Interrupted at His Wr,
Fig. 36a Cross section from Scholar Interrupted at His Writing showing a thin section of the upper layers from the book shadow on the scarf atop the tablecloth, after reduction to 10 microns in thickness, as viewed in transmitted light between crossed polars (photomicrographs and electron micrograph: John Twilley) [comparison viewer]
Cross section from Scholar Interrupted at His Wr,
Fig. 36b Cross section from Scholar Interrupted at His Writing showing the section as viewed using ultraviolet fluorescence microscopy (photomicrographs and electron micrograph: John Twilley) [comparison viewer]
Cross section from Scholar Interrupted at His Wr,
Fig. 36c Cross section from Scholar Interrupted at His Writing showing backscatter electron micrograph showing the dearth of lead white apart from those areas on the left disturbed by lead soap formations from layers beneath. The uppermost layer contains vivianite that has transformed from blue to yellow. Indigo masks the bire fringence of azurite and calcite in the intermediate layers, obscuring distinctions among those layers in transmitted light while they can be differentiated into distinct layers by UV fluorescence microscopy,500x (photomicrographs and electron micrograph: John Twilley) [comparison viewer]
Cross section detail from the scarf over the tabl,
Fig. 37 Cross section detail from the scarf over the tablecloth in Scholar Interrupted at His Writing showing the upper blue strata in the SEM. The low contrast in this backscatter electron image shows the dearth of heavy elements in these layers, including lead white pigment, and implies that they were all intended to be translucent. X-ray spectrometry shows that iron phosphate is common in the top layer (corresponding to the yellow observed in the thin section), and that calcite and gypsum are common in the thicker stratum just beneath. The organic colorant indigo, responsible for blue color in this stratum, is not detectable by this method. Azurite occurs in the lower stratum included in this view, 5,850x (electron micrograph: John Twilley) [comparison viewer]
X-ray spectra from the upper most yellow layer of the scarf in Scholar Interrupted at His Writing (cross hair in Fig. 37) showing a layer composition as a whole, with pigmentation by vivianite and calcite with an ear absence of lead white
Fig. 38a X-ray spectra from the upper most yellow layer of the scarf in Scholar Interrupted at His Writing (cross hair in Fig. 37) showing a layer composition as a whole, with pigmentation by vivianite and calcite with an ear absence of lead white [comparison viewer]
X-ray spectra from the upper most yellow layer of the scarf in Scholar Interrupted at His Writing (cross hair in Fig. 37) showing iron phosphate in individual degraded vivianite particles
Fig. 38b X-ray spectra from the upper most yellow layer of the scarf in Scholar Interrupted at His Writing (cross hair in Fig. 37) showing iron phosphate in individual degraded vivianite particles [comparison viewer]
Partially dispersed pigments from the intermediat,
Fig. 39a Partially dispersed pigments from the intermediate layers from the tablecloth and scarf sequence in Scholar Interrupted at His Writing demonstrating the presence of isotropic indigo along with birefringent calcium carbonate. Polarized light microscopy in transmitted light with polars (photomicrograph: John Twilley) [comparison viewer]
Partially dispersed pigments from the intermediat,
Fig. 39b Partially dispersed pigments from the intermediate layers from the tablecloth and scarf sequence in Scholar Interrupted at His Writing demonstrating the presence of isotropic indigo along with birefringent calcium carbonate. Polarized light microscopy in transmitted light without polars, 1,000x (photomicrograph: John Twilley) [comparison viewer]
Detail of a stripped state photo during treatment,
Fig. 40 Detail of a stripped state photo during treatment of Goat in a Landscape showing losses in the sky along striations of the wood grain at the upper left, revealing the gray dead coloring underneath the uppermost layer of ultramarine (photograph: Nancy Krieg) [comparison viewer]
Cross section of a sample from the sky of Goat i,
Fig. 41a Cross section of a sample from the sky of Goat in a Landscape showing the ground, primuersel, blue-gray dead coloring, and final blue layers, cross section in reflected light (photomicrographs: John Twilley) [comparison viewer]
Cross section of a sample from the sky of Goat i,
Fig. 41b Cross section of a sample from the sky of Goat in a Landscape showing the ground, primuersel, blue-gray dead coloring, and final blue layers, thin section in transmitted light with crossed polars (photomicrographs: John Twilley) [comparison viewer]
Cross section of a sample from the sky of Goat i,
Fig. 41c Cross section of a sample from the sky of Goat in a Landscape showing the ground, primuersel, blue-gray dead coloring, and final blue layers, ultraviolet autofluorescence showing subdivisions in primuersel, 100x (photomicrographs: John Twilley) [comparison viewer]
Dispersed pigments from the sky of Goat in a Lan,
Fig. 42a Dispersed pigments from the sky of Goat in a Landscape showing particles of isotropic natural ultramarine from the uppermost blue stratum that illustrate its great diversity of particle sizes, all in good condition, transmitted light with partially crossed polars, 400x (photomicrographs: John Twilley) [comparison viewer]
Dispersed pigments from the sky of Goat in a Lan,
Fig. 42b Dispersed pigments from the sky of Goat in a Landscape showing particles of isotropic natural ultramarine from the uppermost blue stratum that illustrate its great diversity of particle sizes, all in good condition, transmitted light with partially crossed polars, 400x (photomicrographs: John Twilley) [comparison viewer]
Partially dispersed pigment from the blue-gray de,
Fig. 43 Partially dispersed pigment from the blue-gray dead coloring of the sky of Goat in a Landscape showing fine ultramarine, lead white and black, demonstrating that this was a purposeful blue-gray mixture and not the result of ultramarine degradation, in transmitted light with crossed polars, 400x (photomicrographs: John Twilley) [comparison viewer]
Detail of a leaf in the foreground of Goat in a ,
Fig. 44 Detail of a leaf in the foreground of Goat in a Landscape showing deep blue color and the use of yellow ochre for the vein, field of view: 2.75mm (photomicrograph: John Twilley) [comparison viewer]
Cross section of a sample from the foreground lea,
Fig. 45a Cross section of a sample from the foreground leaf of Goat in a Landscape showing underlying pale yellow application that has been painted out, cross section in darkfield reflected light, 125x (photomicrographs and electron micrograph: John Twilley) [comparison viewer]
Cross section of a sample from the foreground lea,
Fig. 45b Cross section of a sample from the foreground leaf of Goat in a Landscape showing underlying pale yellow application that has been painted out, thin section in transmitted light with crossed polars, 125x (photomicrographs and electron micrograph: John Twilley) [comparison viewer]
Cross section of a sample from the foreground lea,
Fig. 45c Cross section of a sample from the foreground leaf of Goat in a Landscape showing underlying pale yellow application that has been painted out, UV autofluorescence showing yellow-fluorescing lakes, including those in opaque lower layers, 125x (photomicrographs and electron micrograph: John Twilley) [comparison viewer]
Cross section of a sample from the foreground lea,
Fig. 45d Cross section of a sample from the foreground leaf of Goat in a Landscape showing underlying pale yellow application that has been painted out, backscatter electron image showing additional layer differentiation. At least nine layers are present as noted (photomicrographs and electron micrograph: John Twilley) [comparison viewer]
Detail of Herring Seller and a Boy showing mid-tones in the face of the old woman achieved by dark undermodeling, superimposed with translucent flesh tones and additional highlights
Fig. 46 Detail of Herring Seller and a Boy showing mid-tones in the face of the old woman achieved by dark undermodeling, superimposed with translucent flesh tones and additional highlights [comparison viewer]
Detail of Young Woman Holding a Parrot showing the birdcage, an area that represents Dou's working method of painting in sequential planes from the rear to the front
Fig. 47 Detail of Young Woman Holding a Parrot showing the birdcage, an area that represents Dou’s working method of painting in sequential planes from the rear to the front [comparison viewer]
Detail of Scholar Sharpening a Quill showing the brushwork of the proper right hand of the scholar
Fig. 48 Detail of Scholar Sharpening a Quill showing the brushwork of the proper right hand of the scholar [comparison viewer]
Detail of Hermit Praying showing hatching brushwork around the figure’s proper right eye
Fig. 49 Detail of Hermit Praying showing hatching brushwork around the figure’s proper right eye [comparison viewer]
Detail of Hermit Praying showing hatching brushwork along the highlights of the figure’s clenched hands
Fig. 50 Detail of Hermit Praying showing hatching brushwork along the highlights of the figure’s clenched hands [comparison viewer]
Detail of Young Woman Holding a Parrot showing the hatching brushwork along the highlights of the draped curtain
Fig. 51 Detail of Young Woman Holding a Parrot showing the hatching brushwork along the highlights of the draped curtain [comparison viewer]
Detail of Scholar Interrupted at His Writing showing the printed book and handwritten letter in the foreground
Fig. 52 Detail of Scholar Interrupted at His Writing showing the printed book and handwritten letter in the foreground [comparison viewer]
Details of Scholar Interrupted at his Writing s,
Fig. 53a Details of Scholar Interrupted at his Writing showing a “handwritten” text of letter rendered by diluted fine black pigment applied with dithering brushstrokes (photomicrographs: John Twilley) [comparison viewer]
Details of Scholar Interrupted at his Writing s,
Fig. 53b Details of Scholar Interrupted at his Writing showing a “printed” text of the book rendered by thinly dispersed coarse black pigment applied in linear strokes, field of view for both: 2.75mm (photomicrographs: John Twilley) [comparison viewer]
Detail of Scholar Interrupted at His Writing showing the shelf in the background that includes the miniscule letters “…ALVES” on the front of a jar, partially obscured by an overlapping jar
Fig. 54 Detail of Scholar Interrupted at His Writing showing the shelf in the background that includes the miniscule letters “…ALVES” on the front of a jar, partially obscured by an overlapping jar [comparison viewer]
Detail of Goat in a Landscape showing the complex brushwork achieved in rendering the plushness of wavy hair
Fig. 55 Detail of Goat in a Landscape showing the complex brushwork achieved in rendering the plushness of wavy hair [comparison viewer]
Detail of Cat Crouching on the Ledge of an Artist’s Atelier showing the individual bristles and brushstrokes that make up the tabby’s striped pattern
Fig. 56 Detail of Cat Crouching on the Ledge of an Artist’s Atelier showing the individual bristles and brushstrokes that make up the tabby’s striped pattern [comparison viewer]
Detail of Portrait of a Lady in Profile showing individual strands of hair painted in flesh tones that overlay her upper temple
Fig. 57 Detail of Portrait of a Lady in Profile showing individual strands of hair painted in flesh tones that overlay her upper temple [comparison viewer]
Detail of Portrait of a Lady in Profile showing the fur trim painted by dragging the brush back and forth in the adjacent paint
Fig. 58 Detail of Portrait of a Lady in Profile showing the fur trim painted by dragging the brush back and forth in the adjacent paint [comparison viewer]
X-radiograph of Goat in a Landscape showing a change from a profile to frontal view of the goat’s head
Fig. 59a X-radiograph of Goat in a Landscape showing a change from a profile to frontal view of the goat’s head [comparison viewer]
Gerrit Dou, Goat in a Landscape, ca. 1660–65, The Leiden Collection, New York, GD-114
Fig. 59b Gerrit Dou, Goat in a Landscape, ca. 1660–65, oil on panel, 19.5 x24.9 cm, signed, lower center, “GDou” (GD in ligature). The Leiden Collection, New York, GD-114 [comparison viewer]
X-radiograph of Portrait of a Lady with a Music Book showing a change in the arched top and a shift of the figure to the right
Fig. 60a X-radiograph of Portrait of a Lady with a Music Book showing a change in the arched top and a shift of the figure to the right [comparison viewer]
Gerrit Dou, Portrait of a Lady with a Music Book, ca. 1640–44, The Leiden Collection, New York, GD-116
Fig. 60b Gerrit Dou, Portrait of a Lady with a Music Book, ca. 1640–44, oil on panel, 27.1 x 19.8 cm, signed, on the book, “GDou”(GD in ligature). The Leiden Collection, New York, GD-116 [comparison viewer]
Detail of Portrait of a Lady in Profile showing a change in the woman’s upper profile
Fig. 61 Detail of Portrait of a Lady in Profile showing a change in the woman’s upper profile [comparison viewer]
X-radiograph of Old Woman at a Niche by Candlelight showing the original flame of the oil lamp at the center right
Fig. 62a X-radiograph of Old Woman at a Niche by Candlelight showing the original flame of the oil lamp at the center right [comparison viewer]
Gerrit Dou, Old Woman at a Niche by Candlelight, 1671, The Leiden Collection, New York, GD-103
Fig. 62b Gerrit Dou, Old Woman at a Niche by Candlelight, 1671, oil on panel, 26.7 x20.8 cm, signed, bottom center, “GDovAnno 1671”(GD in ligature). The Leiden Collection, New York, GD-103 [comparison viewer]
Stripped-state photo of Old Woman at a Niche by ,
Fig. 63a Stripped-state photo of Old Woman at a Niche by Candlelight (photograph: Nancy Krieg) [comparison viewer]
Detail of a stripped state photo showing the earl,
Fig. 63b Detail of a stripped state photo showing the earlier position of the woman’s proper left arm and hand, which originally rested on the middle of the base of an oil lamp. The original flame of the lamp emerged from the left side of the metal receptacle, where the old woman’s proper left fingers are now located (photograph: Nancy Krieg) [comparison viewer]
Godfried Schalcken,  Conversion of Mary Magdalen, showing a comparabl, 1700,  The Leiden Collection, New York
Fig. 64a Godfried Schalcken, Conversion of Mary Magdalen, signed and dated, lower left: “G. Schalcken/ 1700,”oil on canvas, 94 x 68.6 cm. The Leiden Collection, New York, GS-114, showing a comparable oil lamp with the flame emerging from the side [comparison viewer]
Godfried Schalcken,  Conversion of Mary Magdalen, detail of Conversi, 1700,  The Leiden Collection, New York
Fig. 64b Godfried Schalcken, Conversion of Mary Magdalen, signed and dated, lower left: “G. Schalcken/ 1700,”oil on canvas, 94 x 68.6 cm. The Leiden Collection, New York, GS-114, showing a comparable oil lamp with the flame emerging from the side, detail [comparison viewer]
X-radiograph of Scholar Interrupted at His Writing showing an earlier easel in the background
Fig. 65a X-radiograph of Scholar Interrupted at His Writing showing an earlier easel in the background [comparison viewer]
Gerrit Dou, Scholar Interrupted at His Writing, ca. 1635, The Leiden Collection, New York, GD-102
Fig. 65b Gerrit Dou, Scholar Interrupted at His Writing, ca. 1635, oil on panel, 24.5 x 20 cm, oval, signed, on a piece of paper protruding from the book, “GDov” (GD in ligature). The Leiden Collection, New York, GD-102 [comparison viewer]
Circle of Rembrandt van Rijn, possibly Gerrit Dou,  An Artist in His Studio,  ca. 1630,  The Leiden Collection, New York
Fig. 66 Circle of Rembrandt van Rijn, possibly Gerrit Dou, An Artist in His Studio, ca. 1630, oil on panel, 66.7 x 50.8 cm. The Leiden Collection, New York, GD-112 [comparison viewer]
Detail of Scholar Interrupted at His Writing showing the signature,“GDou,”inserted on a piece of paper on the side of the book.
Fig. 67 Detail of Scholar Interrupted at His Writing showing the signature,“GDou,”inserted on a piece of paper on the side of the book. [comparison viewer]
X-radiograph of Cat Crouching on the Ledge of an Artist’s Atelier
Fig. 68a X-radiograph of Cat Crouching on the Ledge of an Artist’s Atelier [comparison viewer]
X-radiograph superimposed on the visual image,
Fig. 68b Cat Crouching on the Ledge of an Artist’s Atelier, X-radiograph superimposed on the visual image (composite: John Twilley) [comparison viewer]
Infrared image detail showing what appears to be ,
Fig. 69 Infrared image detail showing what appears to be a mousetrap in the lower right corner. InGaAs camera using 1500-1680nm filter (image: Shawn Digney-Peer) [comparison viewer]
Dominicus van Tol,  Boy with a Mousetrap,  ca. 1660–64,  The Leiden Collection, New York
Fig. 70a Dominicus van Tol, Boy with a Mousetrap, ca. 1660–64, oil on panel, 29 x23 cm. The Leiden Collection, New York, DT-100 [comparison viewer]
Dominicus van Tol,  Boy with a Mousetrap, detail,  ca. 1660–64,  The Leiden Collection, New York
Fig. 70b Dominicus van Tol, Boy with a Mousetrap, ca. 1660–64, oil on panel, 29 x23 cm. The Leiden Collection, New York, DT-100, detail [comparison viewer]
Infrared image of Cat Crouching on the Ledge of ,
Fig. 71a Infrared image of Cat Crouching on the Ledge of an Artist’s Atelier showing earlier features such as globe at center left and curtain draped to the left. InGaAs camera using 1500-1680nm filter (image: Shawn Digney-Peer) [comparison viewer]
Infrared image superimposed on X-radiograph with ,
Fig. 71b Infrared image superimposed on X-radiograph with inverted density grayscale, showing earlier drape and architectural details as noted (composite: John Twilley) [comparison viewer]
Panel reverse with bevel indicated by arrows, Cat Crouching on the Ledge of an Artist’s Atelier (photograph: Annette Rupprecht)
Fig. 72a Panel reverse with bevel indicated by arrows, Cat Crouching on the Ledge of an Artist’s Atelier (photograph: Annette Rupprecht) [comparison viewer]
Panel reverse in raking light showing bevel on le,
Fig. 72b Panel reverse in raking light showing bevel on left side only of Cat Crouching on the Ledge of an Artist’s Atelier (photograph: Annette Rupprecht) [comparison viewer]
  1. 1. For an overview of Gerrit Dou’s reputation throughout the centuries, see Arthur K. Wheelock Jr., “Dou’s Reputation,” in Ronni Baer, Gerrit Dou 1613–1675: A Master in the Age of Rembrandt, exh. cat. (Washington, D.C.: National Gallery of Art; London: Dulwich Picture Gallery; The Hague: Royal Cabinet of Paintings Mauritshuis, 2000–2001), 12–24. In the century between the publication of Theopile Thoré’s devastating opinion on Dou in his famous Musées de la Hollande (Paris, 1858–60) and Jan Emmens’s positive reevaluation of Dou in the 1960s, the artist was virtually forgotten. Important studies on Dou since the 1960s include Ronni Baer, “The Paintings of Gerrit Dou (1613–1675)” (PhD diss., New York University, 1990), and the exhibition Gerrit Dou 1613–1675 (see above), curated by Ronni Baer. See esp. pp. 39-42 in this exhibition catalogue, where Baer discusses Dou’s working method.

  2. 2. Luuk Struick van der Loeff and Karin Groen, “Probleem, Overwegingen en Beslissingen bij de Conservatie en Restauratie van het Schilderij door Gerard Dou ‘Jonge Moeder,’ Mauritshuis, 1658, inv.nr. 32,” Centraal Laboratorium Themadag 12 (1987): 40-50. A slightly more elaborate, English version of this article appeared as Luuk Struick van der Loeff and Karin Groen, “The Restoration and Technical Examination of Gerard Dou’s Young Mother in the Mauritshuis,” in ICOM Committee for Conservation: 10th Triennial meeting, Washington, DC, ed. Janet Bridgland (Lawrence, Kansas: Allen Press, 1993), 98–103. In the present article, the English version will be cited.

  3. 3. Struik van der Loeff and Groen, “Restoration,” 100: Dou not only changed the position of the head of the young girl behind the cradle, he also appears to have adjusted the date from 1652/3 to 1658, possibly because the original commission of the painting was abandoned in 1652/3 due to the death of the patron. Dou probably revisited the painting in 1658, just before it was purchased by the Staten van Holland and West-Friesland to be part of the 1660 diplomatic “Dutch gift” to Charles II, king of England.

  4. 4. Struik van der Loeff and Groen, “Restoration,” 102–3. Struick van der Loeff and Groen noted the presence of an astonishing twelve layers of alternating brown and black paint underneath the yellow of the lamp.

  5. 5. Eric Jan Sluijter, De lof der schilderkunst: Over schilderijen van Gerrit Dou (1613–1675) en een traktaat van Philips Angel uit 1642 (Hilversum: Verloren, 1993.

  6. 6. Sluijter, Lof der schilderkunst, 58–71: this combination of a high level of detail and loose brushstrokes was already noted by (near-) contemporary art theorists and biographers. In his Nieuwe Schouburgh (The Hague, 1750), vol. 2, p. 4, Johan van Gool speaks of a “zwierige lossigheit,” and Philips Angel in his Lof der Schilderkonst (Leiden, 1642) of “eyghentlijck,” as well as “los,” which can mean realistic as well as loose. Sluijter further remarks that Karel van Mander used exactly this contrast to describe the work of Lucas van Leyden, Dou’s famous early sixteenth-century predecessor, and suggests that Dou was modeling himself after Lucas’s work, whether he was conscious of it or not.

  7. 7. Friso Lammertse, “Veranderen na verloop van jaren: Over Gerard Dou’s Kwakzalver in Rotterdam en het Zelfportret in Kansas City,” in Album Discipulorum J. R. J. van Asperen de Boer, ed. Peter van den Brink and Liesbeth M. Helmus (Zwolle: Waanders, 1997), 111–20, esp. 116–19. Both works include the later 1667 design of the Blauwe Poort gate. In both cases, it appears that Dou was not reworking an already existing gate, but rather added the entire gate in or after 1667. In the case of the Kansas City Self-Portrait, Dou also added other elements, such as the carpet under his proper right arm, at the same time that he added the gate.

  8. 8. Annetje Boersma, “Dou’s Painting Technique: An Examination of Two Paintings,” in Gerrit Dou 1613–1675, exh. cat. (see note 1 above), 54–63.

  9. 9. Boersma, “Dou’s Painting Technique,” 59: whereas the finely ground ultramarine Dou used for his blue pigment in the Rotterdam Lady at Her Toilet is well preserved, the blues in the curtain, the mother’s skirt, and the cradle blanket in the Mauritshuis Young Mother are now a faded gray. See also Struik van der Loeff and Groen, “Restoration,” 101, who first mention this discoloration of the ultramarine in the Young Mother.

  10. 10. Jørgen Wadum, “Dou Doesn’t Paint, Oh No, He Juggles with His Brush: Gerrit Dou, a Rembrandtesque Fijnschilder,” ArtMatters 1 (2002): 62–77.

  11. 11. For an overview of the paintings by Gerrit Dou in this group, see Arthur K. Wheelock Jr., ed., The Leiden Collection Catalogue (forthcoming; web publication, 2014, www.theleidencollection.com).

  12. 12. For the attribution to Dou of an early painting in this group, Artist at his Easel (GD-112), dated to ca. 1630 (see fig. 66), as well as of Two Old Men Disputing (St. Peter and St)  (GD-101), ca. 1630 (previously attributed to the circle of Rembrandt), and Elderly Man (GD-109), after 1640, another work initially thought to be in the circle of Dou, see Wheelock, The Leiden Collection Catalogue (see note 11 above).

  13. 13. Refer to the Appendix for details of the methods employed. All X-radiographs, IR images, dendrochronological reports, and reports of John Twilley’s analytical work are kept on file at the Leiden Collection.

  14. 14. See Christoph Schölzel, “The Technique of the Leiden Fijnschilders,” in The Leiden Fijnschilders from Dresden, ed. Annegret Laabs, exh. cat. (Dresden: Gemäldegalerie Alte Meister; Leiden: Museum De Lakenhal, 2000–2001), 16–24, esp. 16.

  15. 15. For a discussion of the decline of the oak wood trade with the Baltic, mostly due to Polish-Swedish wars in 1626–29 and 1650–55, see Jo Kirby, “Studio Practice and the Training of Artists,” in Art in the Making: Rembrandt, ed. David Bomford (New Haven: Yale University Press, 2006), 14–26, esp. 23.

  16. 16. Ian Tyers, “Tree-Ring Analysis of Scholar Interrupted at His Writing, GD-102,” unpublished dendrochronological report, November 2010, curatorial files, The Leiden Collection: the tree rings match the Eastern Baltic reference data, and the youngest annual ring dates to 1592. This suggests an earliest possible felling date of 1601 with nine sapwood rings (minimum), and an earliest possible production date of 1603 (adding two years for seasoning and transport); a more likely felling date is 1607 with fifteen sapwood rings (median), and a more likely possible production date is 1609 (adding two years for seasoning and transport). In the following references to dendrochronological reports, only the youngest annual ring will be noted. Ian Tyers, “Tree-Ring Analysis of Portrait of a Lady with a Music Book, GD-116,” unpublished dendrochronological report, November 2010, curatorial files, The Leiden Collection: the tree rings match the Eastern Baltic reference data, and the youngest annual ring dates to 1606, indicating a possible felling date.

  17. 17. Ian Tyers, “Tree-Ring Analysis of Herring Seller and a Boy, GD-106,” unpublished dendrochronological report, November 2010, curatorial files, The Leiden Collection: the tree rings match the German and French reference data, and the youngest annual ring dates to 1637.

  18. 18. Boersma, “Dou’s Painting Technique,” 58.

  19. 19. Ian Tyers, “Tree-Ring Analysis ofScholar Interrupted at His Writing, GD-102” unpublished dendrochronological report, November 2010, curatorial files, The Leiden Collection: the youngest annual ring was formed in1592; Ian Tyers, “Tree-Ring Analysis of Goat in a Landscape, GD-114,” unpublished dendrochronological report, November 2010, curatorial files, The Leiden Collection: the youngest annual ring was formed in 1586, and Ian Tyers, “Tree-Ring Analysis ofCat Crouching on the Ledge of an Artist’s Atelier, GD-108,” unpublished dendrochronological report, November 2010, curatorial files, The Leiden Collection: the youngest annual ring was formed in 1580.

  20. 20. Ian Tyers, “Tree-Ring Analysis of Cat Crouching on the Ledge of an Artist’s Atelier, GD-108,” unpublished dendrochronological report, November 2010, curatorial files, The Leiden Collection. It is important to note that these early dates may also be explained by the small size of the panels. Since small panels do not necessarily contain the whole width of a tree, only older wood from the center of the tree may be included.

  21. 21. Ian Tyers, email communication, July 25, 2013, curatorial files, The Leiden Collection. The first wood sawmill in Leiden, De Ruyter, was most likely built in 1628, close to the Boshuizersluis, and it appears to have been the only one in Leiden during Dou’s lifetime. The authors are grateful to Christiaan Vogelaar, email communication, July 31, 2013, for bringing De Ruyter to our attention; some information can be found on the Heritage website of the city of Leiden. (consulted July 31, 2013). By 1663, this mill was owned by the renowned Leiden carpenter Jan van Ackeren, who had worked on the design of the classicist Loridanshof, and whom Dou would have known personally. See the online Dutch windmill database, (consulted July 31, 2013): Van Ackeren gained permission to move his mill from the Boshuizersluis to the other side of the Haagweg, where transport possibilities were much better. It can be assumed that most Dou panels in the Leiden Collection were cut mechanically, presumably in such a mill, if not at De Ruyter itself.

  22. 22. Kirby, “Studio Practice,” 23: these craftsmen were members of the joiners’ and cabinetmakers’ guild. The administration of the Leiden guild of the joiners has not survived. The authors thank Piet Bakker, email communication, August 12, 2013, who conveyed that, based on his database research, at least 150 joiners and cabinetmakers are listed in Leiden in the seventeenth century.

  23. 23. For a discussion on beveling, see Schölzel, “Technique,” 16–17. See also Ernst van de Wetering, Rembrandt: The Painter at Work, rev. ed. (Amsterdam: Amsterdam University Press, 2009; first ed., 1997), 11.

  24. 24. See Van de Wetering, Painter at Work, 11–12, for the discussion of beveling and the cutting of wood: panels had less tendency to warp when cut in this fashion.

  25. 25. Panel-maker marks are often applied with a branding iron on the reverse of the panel, identifying the panel maker as well as the guild. For a discussion of paintings executed in Antwerp, where it appears to have been quite common to use such marks because of the regulations of the Antwerp guild of St. Luke, see Jørgen Wadum, “Recent Discoveriers on Antwerp Panel Makers’ Marks,” Technologia Artis (1993): 96–100.

  26. 26. Kirby, “Studio Practice,” 23.

  27. 27. Van de Wetering, Painter at Work, 13: the clusters range from the smallest size of ca. 15.5 x 12.7 cm, to the largest size of ca. 123.6 x 89.5 cm. It is only when Rembrandt moved to Amsterdam that he stepped away from the somewhat restricted Leiden panel sizes and started to experiment with canvas and less standard panel sizes.

  28. 28. Schölzel, “Technique,” 24: here, the clusters range from the smallest size of ca. 26 x 20 cm to the largest size of ca. 61 x 45 cm.

  29. 29. Schölzel, “Technique,” 24: note that this size falls into the second category on Van de Wetering’s list (Van de Wetering’s smallest category measures ca. 15.5 x 12 cm). Other panels from the Leiden Collection fall under Schölzel’s categories four are ca. 33 x 26 cm; five, ca. 43 x 34 cm, and six, ca. 61 x 45 cm.

  30. 30. Schölzel, “Technique,” 24: in the first group, Schölzel notes four paintings by Dou and one by Willem van Mieris. He also records one Dou in the third category, two in the fourth, three in the fifth, and one in the last category.

  31. 31. See Ronni Baer, “Portrait of a Woman,” in Gerrit Dou 1613–1675, exh. cat. (see note 1 above), 82-83, no. 10. See also Dominique Surh, “Portrait of a Lady in Profile,” in The Leiden Collection Catalogue (see note 11 above), for her correspondence with Marieke de Winkel regarding clues about the dating based on the sitter’s dress.

  32. 32. Ian Tyers, “Tree-Ring Analysis of Portrait of a Lady in Profile, GD-110,” unpublished dendrochronological report, November 2010, curatorial files, The Leiden Collection. Since the oval panel is firmly set into the larger panel, dendrochronological examination of the oval panel is not possible through traditional means at this time.

  33. 33. See Anja K. Ševčík and Jiří Třeštík, “Doorstep Transactions: Structural and Compositional Transformations on Gerard Dou’s Young Lady on a Balcony,” Bulletin of the National Gallery in Prague 22-23 (2012-13): 23-43 . For a partial list of these unusual constructions in Dou’s oeuvre, see also Ronni Baer, “Of Cats and Dogs: Domestic Pets in Rembrandt and Dou,” in Een Kroniek voor Jeroen Giltaij: Kroniek van het Rembrandthuis (Amsterdam: Rembrandthuis, 2012): 63–69, esp. 66, 67 n 16. For a survey of format changes, including inlaid panels, in the work of Dou’s pupil Frans van Mieris, see Quentin Buvelot and Otto Naumann, “Format Changes in the Work by Frans van Mieris the Elder,” Burlington Magazine 150 (2008): 102–4.

  34. 34. John Twilley, “Scientific Examination of Portrait of Dirck van Beresteyn by Gerrit Dou (GD-111),” unpublished report, dated February 23, 2012, curatorial files, The Leiden Collection. For a recent publication on this painting, see Ronni Baer, “Dou and the Delft Connection: The Portrait of Dirk van Beresteyn,” in Face Book: Studies on Dutch and Flemish Portraiture of the 16th-18th Centuries; Liber Amicorum Presented to Rudolf E. O. Ekkart on the Occasion of His 65th Birthday, ed. Edwin Buijsen, Charles Dumas, and Volker Manuth (Leiden: Primavera Pers, 2012), 279–84.

  35. 35. For a discussion of the possible function of this tiny portrait, see Dominique Surh, “Portrait of Dirck van Beresteyn,” in The Leiden Collection Catalogue (see note 11 above).

  36. 36. Ernst van de Wetering cites a 1676 document preserved in the Leiden municipal archives, which provides an interesting case for suggesting that Leiden artists relied on the services of a single primer. The authors are grateful to Piet Bakker for providing a transcription of the passage (email communication, August 11, 2013) that clarifies the account. It appears that Dirck de Lorme (ca. 1635–ca. 1673) was the ebony worker (ebbenhoutwerker) who held the monopoly for priming canvases and panels in Leiden up until his death, and that Leendeert van Nes made the petition in 1676 to take over this service, rather than the other way around as described by Van de Wetering. See Van de Wetering, Painter at Work, 22 n 29. For other discussions of the ground layer during this period, see also Ashok Roy, “The Ground Layer: Function and Type,” in Art in the Making: Rembrandt, ed. David Bomford (New Haven: Yale University Press, 2006), 27–29, esp. 27; and Melanie Gifford, “Lievens’ Technique: ‘Wonders in Smeared Paint, Varnishes, and Oils,’” in Jan Lievens: A Dutch Master Rediscovered, ed. Arthur K. Wheelock Jr., exh. cat. (Washington, D.C.: National Gallery of Art; Milwaukee Art Museum; Amsterdam: Rembrandthuis, 2008–9), 40–53, esp. 42.

  37. 37. Struik van der Loeff and Groen, “Restoration,” and Boersma, “Dou’s Painting Technique,” 58.

  38. 38. Struik van der Loeff and Groen, “Restoration,” 100.

  39. 39. At the far right side of the Scholar Interrupted at His Writing, the area of the support bar of the globe is thinly painted and lies atop what appears to be the bare wood of the panel, visible through the craquelure. See John Twilley, “Scientific Examination of Scholar Interrupted at His Writing by Gerrit Dou (GD-102),” unpublished report dated April 2011, curatorial files, The Leiden Collection. In a painting from the early 1660s, Goat in a Landscape, the ground structure appears more uniform at the two sample locations taken in the areas of the sky and foliage. The ground layer recovered with both samples was based first upon lead white, followed by a thin tan stratum, rich in earth pigments, probably a primuersel. See John Twilley, “Scientific Examination of Goat in a Landscape by Gerrit Dou (GD-114),” unpublished report dated February 2013, curatorial files, The Leiden Collection.

  40. 40. In the life of Hieronymous Bosch, Karel van Mander describes a primuersel as the transparent layer applied directly over the line underdrawing on top of the ground. Karel Van Mander, Het Schilder-Boeck (Haarlem: Paschier van Wesbysch, 1604), fol. 216v; for an English translation, see Karel van Mander, The Lives of the Illustrious Netherlandish and German Painters, from the First Edition of the ‘Schilder-boeck’ (1603–1604), trans. and ed. Hessel Miedema (Doornspijk: Davaco, 1994).

  41. 41. Wadum, “Dou Doesn’t Paint,’” 66. Wadum does not differentiate between the ground applied by the primer and the upper ground, or the primuersel, applied by the artist, and refers more generally to the ground as being light or buff colored.

  42. 42. John Twilley, “Scientific Examination of Scholar Interrupted at His Writing by Gerrit Dou (GD-102),” unpublished report dated April 2011, curatorial files, The Leiden Collection.

  43. 43. John Twilley, “Scientific Examination of Goat in a Landscape by Gerrit Dou (GD-114),” unpublished report dated February 2013, curatorial files, The Leiden Collection.

  44. 44. Wadum, “Dou doesn’t paint,” 65.

  45. 45. For a list of paintings in which Wadum found partial, or fragmented, underdrawings, see Wadum, “Dou Doesn’t Paint,” 65–66.

  46. 46. While carbon-based underdrawings are virtually absent in Rembrandt’s painting, his own teacher, Pieter Lastman, seems to have executed preparatory underdrawings. An elaborate drawing was found in the infrared photograph of David and Uriah (1619, oil on panel, 41.6 x 62.5 cm; The Leiden Collection, New York, inv. no. PL-100). In this example, Lastman adhered closely to his initial conception and changed only a few minor details during the subsequent painting process, for instance, the position of the head of David’s dog. See Annette Rupprecht,“Technical Notes of David and Uriah by Pieter Lastman, PL-100,” unpublished report dated March 2012, curatorial files, The Leiden Collection, and Rachel Pollack, “David and Uriah by Pieter Lastman,” in The Leiden Collection Catalogue (see note 11 above).

  47. 47. In addition to the possibility of a medium lacking carbon black, another explanation for the appearance of Dou’s “fragmented” underdrawings, could be that subsequent paint layers further obscure them. However, certain examples, such as the Hermit Praying, lack any areas that are obscured by IR-absorbing pigments and yet possess sketch lines prominent in some areas and absent in many others.

  48. 48. The authors are thankful to Dr. Tico Seifert of the National Gallery of Scotland for confirming that similar line underdrawings were found in the window panes, figure, and in isolated areas of the tablecloth in Dou’s earliest dated painting, the 1637 Violin Player (Edinburgh, National Gallery of Scotland), painted within a few years of the Scholar Interrupted, email communication, July 30, 2013. The authors are also grateful to Dr. Seifert for providing X-radiograph and IR photographs for study in July 2013. Groen and Struick van der Loeff indicated that the Young Mother at the Mauritshuis contains a clear underdrawing, most likely in carbon black along the folds of the mother’s skirt. They noted that the lines appear uniform and were drawn as though guided by the straight edge of a ruler. Struik van der Loeff and Groen, “Restoration,” 100–101. The authors would also like to thank Petria Noble of the Royal Cabinet of Paintings Mauritshuis for providing X-radiographs and IR photographs of Dou’s 1658 Young Mother for study in July 2013.

  49. 49. Here, however, the dark hatchings that appear in the IR photograph follow the final result of the paint layer so closely that it cannot be determined with absolute certainty whether the IR photograph reveals an underdrawing, and not the paint layers.

  50. 50. According to Gerard de Lairesse’s Het groot Schilderboeck of 1707, there are four stages in the painting process: “inventing,” the “dead coloring,” the second coloring or “working up,” and the “retouching” or finishing. See Van de Wetering, Painter at Work, 27 n 43; David Bomford, “The Paint Layers,” in Art in the Making: Rembrandt (see note 36 above), 30–34, esp. note 2.

  51. 51. Wadum notes that Dou would “delineate the composition in bluntly applied brush strokes of varying thickness before spreading the undermodeling in monochrome hues.” Wadum, “Dou Doesn’t Paint,” 67. In Rembrandt’s Concord of the State, from ca. 1640 (Rotterdam, Museum Boijmans van Beuningen), an underlying compositional sketch was found, which Van de Wetering cites as an example of Rembrandt’s laying in simultaneously the monochrome dead coloring with a sketch in a “provisionally completed whole.” Van de Wetering, Painter at Work, 27. Thus it seems plausible that Dou may have also handled the sketch phase as synonymous with the dead coloring.

  52. 52. Wadum, “Dou Doesn’t Paint,” 67.

  53. 53. John Twilley, “Scientific Examination of An Old Scholar Sharpening a Quill by Gerrit Dou (GD-104),” unpublished report dated January 2013, curatorial files, The Leiden Collection.

  54. 54. For a discussion about the pigment samples and their cross sections, see John Twilley, “Scientific Examination of Goat in a Landscape by Gerrit Dou (GD-114),” unpublished report dated February 2013, curatorial files, The Leiden Collection. For a general technical overview with notes about its recent conservation history, see Annette Rupprecht, “Technical Notes of Goat in a Landscape by Gerrit Dou, GD-114,” unpublished report dated August 2011, curatorial files, The Leiden Collection.

  55. 55. There was seldom the opportunity to take cross sections for stratigraphic analysis in important areas of the compositions and, accordingly, pigment identifications are more numerous from the uppermost layers or more heavily painted areas. Cross sections were prepared when feasible.

  56. 56. Raman spectroscopy, often highly effective on isolated pigments, is seldom successful on embedded cross sections of dried oil paint. The sample quantities required for chromatographic methods of lake pigment identification were unacceptable for these small paintings.

  57. 57. Lead-fatty acid soaps are the reaction products of lead, derived from lead-based pigments, interacting with free fatty acids, liberated from the drying oils in the medium. Over time, small nodules of these products may erupt from the paint surface, giving rise to minute blemishes that catch and scatter the light. Even when not visible on the paint surface their development was frequently noted during laboratory study.

  58. 58. The alteration of smalt occurs by decomposition of the powdered glass of which it is composed, usually with the loss of the cobalt responsible for its color. The process proceeds from the exterior to the interior of each individual grain so that small particles may be affected throughout, while coarse ones acquire a “rind” from which the color has been lost around an intact core. Neither condition was evident in the samples from this painting, which retain brilliant saturated color throughout a wide range of particle sizes. Discussions of the forms of smalt alteration, its underlying causes and the means of its recognition can be found in the following references: Laurianne Robinet, Marika Spring, and Sandrine Pages-Camagna, “Vibrational Spectroscopy Correlated with Elemental Analysis for the Investigation of Smalt Pigment and Its Alteration in Paintings,” Analytical Methods 5 (2013): 4628–38 http://dx.doi.org/10.1039/c3ay40906f ; Jaap J. Boon et al., “Imaging Microspectroscopic, Secondary Ion Mass Spectrometric and Electron Microscopic Studies on Discoloured and Partially Discoloured Smalt in Cross sections of 16th-Century Paintings,” Chimia 55 (2001): 952–60.

  59. 59. E.-L. Richter, “Seltene Pigmente im Mittelalter,” Zeitschrift für Kunsttechnologie und Konservierung 2 (1988): 171–77; Mark Richter, “Shedding Some New Light on the Blue Pigment ‘Vivianite’ in Technical Documentary Sources of Northern Europe,” ArtMatters 4 (2007): 37–53; H. Stege et al., “Vivianit — Neue Nachweise des Pigmentes und seine charakteristischen Veränderungen in der niederländischen Malerei des 17. Jahrhunderts,” in Archäometrie und Denkmalpflege — Kurzberichte, ed. O. Hahn and H. Stege, (Bochum: Bergbau-Museum Bochum, 2006), 81–83.

  60. 60. Vivianite has long been known to undergo oxidation of its iron accompanied by the breakdown of the crystallinity of the mineral. T. L. Watson, “The Colour Change in Vivianite and Its Effects on the Optical Properties,” American Mineralogist 3 (1918): 159–61; John Twilley, “Polychrome Decorations on Far Eastern Gilt Bronze Sculpture of the Eighth Century,” in Scientific Research on the Sculptural Arts of Asia: Proceedings of the Third Forbes Symposium at the Freer Gallery of Art, eds. Janet G. Douglas, Paul Jett, and John Winter (London: Archetype, 2007), 174–87 (Figures 10a, e, and f in this reference show the dramatic color change associated with the alteration of paint consisting solely of vivianite); J. O. Nriagu, “Stability of Vivianite and Ion-Pair Formation in the System Fe3(PO4)2–H3PO4–H2O,” Geochimica et Cosmochimica Acta 36 (1972): 459–70 http://dx.doi.org/10.1016/0016-7037(72)90035-X ; David A. Scott and Gerhard Eggert, “The Vicissitudes of Vivianite as Pigment and Corrosion Product,” Reviews in Conservation 8 (2007): 3–13. The concept that all iron phosphate pigment occurrences constitute “vivianite” is an oversimplification, since the mineralogical literature describes several related, but distinct, compounds including metavivianite and ferrostrunzite. While these contain some ferric iron and often possess colors ranging from blue to brown, testing by methods capable of distinguishing between these iron phosphates has shown that metavivianite has also been employed in painting and can sometimes retain a blue color. See Hartmut Kutzke et al.,“Alteration of Vivianite Pigments in Paint Layers of 17th-Century Oil Paintings,” ESRF Experiment #ME-1199, March 1, 2006 (http:ftp.esrf.eu/pub/UserReports/32509_A.pdf; accessed, February 3, 2011). The authors cite the occurrence of vivianite in a sample from Dou’s 1646 The Praying Anchorite. While artists of the seventeenth century lacked the means to fully know or control what was in their pigments, we can expect that someone devoting the attention to his work that Dou displays would have been very selective in choosing among these highly variable materials.

  61. 61. Margriet van Eikema Hommes, “Indigo as a Pigment in Oil Painting and Its Fading Problems,” in Changing Pictures: Discoloration in 15th-17th Century Oil Paintings (London: Archetype, 2004).

  62. 62. The pervasive application of such a costly pigment may reflect the preference of the painting’s original owner, Johan de Bye. For a discussion of the painting, its meaning, and early ownership by De Bye, see Dominique Surh, “Goat in a Landscape,” in The Leiden Collection Catalogue (see note 11 above).

  63. 63. John Twilley, “Scientific Examination of Goat in a Landscape by Gerrit Dou (GD-114),” unpublished report dated February 2013, curatorial files, The Leiden Collection.

  64. 64. A“lake” pigment is composed of soluble organic color of the type used in the dyeing of fabric that has been immobilized on a colorless carrier such as chalk, alumina, or gypsum so that it can function as a pigment. Lakes are typically less resistant to light-fading than mineral pigments.

  65. 65. The color saturation of this yellow was low in all places where it occurs, even those beneath opaque layers that could be expected to have sheltered it from fading. These lower layers, which comprise a yellow application covered over by the leaf that was not part of its construction, were not intended to influence the layers above. Differentiation of all strata comprising the foliage sample required the application of all four methods of sample preparation illustrated in figure 39a-d. However, it was impossible to isolate any examples of the yellow lake for other forms of analysis or, often, to differentiate the lake from its neighbors during scanning electron microscopy. No lead-tin yellow or orpiment was found in the yellows. John Twilley, “Scientific Examination of Goat in a Landscape by Gerrit Dou (GD-114),” unpublished report dated February 2013, curatorial files, The Leiden Collection.

  66. 66. For an overview of Rembrandt’s similar working order, which follows a widespread practice in the seventeenth century, see Van de Wetering, Rembrandt: The Painter at Work, 32–44, 45 n 54.

  67. 67. For an example of Dou leaving an area unpainted in reserve, see John Twilley, “Scientific Examination of Cat Crouching on the Ledge of an Artist’s Atelier by Gerrit Dou (GD-108),” unpublished report dated December 2013, curatorial files, The Leiden Collection.

  68. 68. For a detailed account of the sequence of painting in this area as indicated by the overlapping layers of paint, see John Twilley, “Scientific Examination of Young Woman Holding a Parrot by Gerrit Dou (GD-105),” unpublished report dated February 2014, curatorial files, The Leiden Collection.

  69. 69. Baer, “The Paintings of Gerrit Dou,” nos. 113, 116; Baer, Gerrit Dou 1613-1675, 112, 130, 132;Sluijter, Lof der schilderkunst, 58; Wadum, “Dou Doesn’t Paint,” 68–69.

  70. 70. Wadum, “Dou Doesn’t Paint,” 68–69.

  71. 71. John Twilley, “Scientific Examination of Scholar Interrupted at His Writing by Gerrit Dou (GD-102),” unpublished report dated April 2011, curatorial files, The Leiden Collection. It is unclear which word is partially represented; for a fuller discussion of the iconography, see Dominique Surh, “Scholar Interrupted at His Writing” in The Leiden Collection Catalogue (see note 11 above).

  72. 72. The X-radiograph indicates that the rectangular composition was initially conceived as an arched top. The greater visibility of the arch along the upper right-hand side coincides with the direction of the fall of light onto this area and accounts for the greater content of lead white in the underlying paint. Dou seems to have positioned the figure centrally underneath this arch, and when he later added the asymmetrical curtain, he shifted the figure to the right in order to allow for a more even distribution of background space surrounding the woman’s head. See Dominique Surh, “Portrait of a Lady with a Music Book,” in The Leiden Collection Catalogue (see note 11 above).

  73. 73. Annette Rupprecht, “Technical Notes of Old Woman at a Niche by Candlelight by Gerrit Dou, GD-103,” unpublished report dated March 2012, curatorial files, The Leiden Collection, has noted a slightly raised triangular shape near the base of the old woman’s left hand where the artist painted the top of the oil lamp, visible in the X-radiograph, and infrared photograph, as well as in the raking light photograph.

  74. 74. A similar oil lamp is also found in Gerrit Dou’s Old Woman with Two Young Children, ca. 1655, (Boston, Museum of Fine Arts), see Ronni Baer, “A Dou for Boston,” in Collected Opinions: Essays on Netherlandish Art in Honour of Alfred Bader, eds. Volker Manuth and Axel Rüger (London: Paul Holberton, 2004), 18–25, esp. 21.

  75. 75. Baer, “The Paintings of Gerrit Dou,” no. 14; Ronni Baer, “Man Interrupted at His Writing,” in Gerrit Dou 1613–1675, exh. cat. (see note 1 above), 70–71, no. 4.

  76. 76. For an overview of Dou’s depictions of the artist at work, see R. W. Hunnewell, “Gerrit Dou’s Self Portraits and Depictions of the Artist” (PhD diss., Boston University, 1983).

  77. 77. For a discussion of the attribution history of the Artist at His Easel, ca. 1630, oil on panel, 66.7 x 50.8 cm; The Leiden Collection (GD-112), see Dominique Surh, “Artist at His Easel,” in The Leiden Collection Catalogue (see note 11 above). Two other paintings with similar subject matter are illustrated in Gerrit Dou 1613–1675, exh. cat. (see note 1 above), 64–65, no. 1; 68–69, no. 3.

  78. 78. A parasol frequently appears in Dou’s later paintings, particularly in his own self-portraits, in conjunction with an easel in the background; for example, his Self-Portrait of 1647 in the Dresden Gemäldegalerie Alte Meister. A parasol also appears in The Quack in the Boijmans Museum in Rotterdam to highlight the subject, who performs to an audience of gullible listeners. On the parallel between the artist and the quack in working deception, see J. A. Emmens, “De Kwakzalver: Gerrit Dou (1613–1675),” Openbaar Kunstbezit 15 (1971): 4a-b; Ivan Gaskell, “Gerrit Dou, His Patrons and the Art of Painting,” Oxford Art Journal 5, no. 1 (March 1982): 18–20 http://dx.doi.org/10.1093/oxartj/5.1.15 ; and Svetlana Alpers, The Art of Describing (Chicago: University of Chicago Press, 1983), 116–18. It is not clear whether Dou’s inclusion of the parasol in the Scholar Interrupted at His Writing is also a reference to deception.

  79. 79. In his 2002 publication, Jørgum Wadum observed that in an earlier composition the large book in the Scholar Interrupted at His Writing was originally planned to lie flat on the table. Our X-radiograph and IR photograph (at 1500 nanometers) does not indicate any such change in the position of the book, so it remains unclear as to what his comment precisely refers. Nevertheless, his explanation does address some of the otherwise perplexing changes that consist of broad features seen in IR photography in the bottom foreground that have no parallels in the final painting. See Wadum, “Dou Doesn’t Paint,” 69 n 46.

  80. 80. Annette Rupprecht, “Technical Notes of Scholar Interrupted at His Writing by Gerrit Dou, GD-102,” unpublished report dated March 2011, curatorial files, The Leiden Collection.

  81. 81. Baer mentions the possible influence of Rembrandt in his portraits from the early 1630s, where he placed his signature in a letter or paper held by the subject; see Ronni Baer, “Man Interrupted at His Writing,” in Gerrit Dou 1613–1675, exh. cat. (see note 1 above), 70–71, no. 4 n 4, 136.

  82. 82. See Junko Aono, “Boy with a Mousetrap by Candlelight by Dominicus van Tol,” in The Leiden Collection Catalogue (see note 11 above), in which a boy holds a similar mousetrap with a diagonal lever at the top that would have controlled the trapping mechanism.

  83. 83. Baer suggests that the young woman originally belonged to a separate composition and that when she was painted out, the cat and the curtain were painted in. She speculates that the young woman was intended as part of an independent kitchen scene and was shown leaning forward to pour from a jug. For Dou’s earlier treatment of the subject in Kitchen Scene, late 1640s, oil on panel, 41.3 x 30.5 cm; Copenhagen, Statens Museum for Kunst, and The Mousetrap, ca. 1650, signed, oil on panel 47 x 36 cm; Montpellier, Musée Fabre, and Girl with a Cat and Mousetrap (formerly Sotheby’s, London, July 3, 2013, no. 13; now with Adam Williams, New York), see Ronni Baer, “Of Cats and Dogs,” 67–68, 69 n 19, fig. 4.

  84. 84. The image of a cat watching a mousetrap first appeared in Daniel Heinsius’s popular book of love emblems from 1608, Emblemata amatoria, where it symbolized the ensnarement of love, with the weary, trapped mouse representing the love-struck soul and the cat embodying the lust that ultimately does in its prey. Heinsius’s twentieth emblem depicts a mouse inside a wooden trap, too frightened to come out for fear of the lurking cat who keeps watch beside it, while a mischievous Cupid with his bow and arrow iterates the underlying theme of love. Daniel Heinsius, Emblemata Amatoria (Amsterdam, 1608), fol. 20. For a fuller discussion of the iconography, see Dominique Surh, “Cat Crouching on the Ledge of an Artist’s Atelier” in The Leiden Collection Catalogue (see note 11 above.

  85. 85. Neither the ground nor the paint layer itself extends over the edges of the panel. See Annette Rupprecht, “Technical Notes of Cat Crouching on the Ledge of an Artist’s Atelier by Gerrit Dou GD-108,” unpublished report dated March 2012, curatorial files, The Leiden Collection.

  86. 86. Left in reserve, the globe itself appears not to have been painted but merely planned. See John Twilley, “Scientific Examination of Cat Crouching on the Ledge of an Artist’s Atelier by Gerrit Dou (GD-108),” unpublished report dated December 2013, curatorial files, The Leiden Collection.

  87. 87. Cat Crouching on the Ledge of an Artist’s Atelier is unusual in its iconographic simplicity. Baer has observed that the tail of a mouse emerges from underneath the proper left paw of the cat, but this observation appears to be a misreading of an area of exposed ground where two areas of dark paint originally conjoined. See Baer, “Of Cats and Dogs,” 66.

  88. 88. Eric Jan Sluijter, “Venus, Visus, and Pictura,” in Seductress of Sight: Studies in Dutch Art of the Golden Age (Zwolle: Waanders, 2000), 87–159, esp. 90–99.

  89. 89. For a similar interpretation, see Baer, “Of Cats and Dogs,” 66-69. On the wide range of meanings associated with the representation of the cat in the seventeenth century, see Susan Donahue Kuretsky, “Rembrandt’s Cat,” in Aemulatio Imitation: Emulation and Invention in Netherlandish Art from 1500 to 1800; Essays in Honor of Eric Jan Sluijter, ed. Anton W. A. Boschloo, Nicolette C. Sluijter-Seijffert, Jacquelyn N. Coutre, and Stephanie S. Dickey (Zwolle: Waanders, 2011), 263–76.

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Watson, T. L. “The Colour Change in Vivianite and Its Effects on the Optical Properties.” American Mineralogist 3 (1918): 159–61.

Wetering, Ernst van de. Rembrandt: The Painter at Work. Rev. ed. Amsterdam: Amsterdam University Press, 2009; first ed., 1997.

Wheelock, Arthur K., Jr. “Dou’s Reputation.” In Ronni Baer, Gerrit Dou 1613–1675: A Master in the Age of Rembrandt, 12–24 (see above).

Wheelock, Arthur K., Jr., ed. The Leiden Collection Catalogue. Online publication, forthcoming, 2014, www.theleidencollection.com.

List of Illustrations

Gerrit Dou,  Scholar Sharpening a Quill,  ca. 1630–35,  The Leiden Collection, New York
Fig. 1a Gerrit Dou, Scholar Sharpening a Quill, ca. 1630–35, oil on panel, 25 x 20.5 cm, oval, signed, center right, under quill, “GD”(GD in ligature). The Leiden Collection, New York, GD-104 [comparison viewer]
Gerrit Dou,  Scholar Sharpening a Quill, verso,  ca. 1630–35,  The Leiden Collection, New York
Fig. 1b Gerrit Dou, Scholar Sharpening a Quill, verso,  ca. 1630–35,  The Leiden Collection, New York [comparison viewer]
Gerrit Dou,  Scholar Interrupted at His Writing,  ca. 1635,  The Leiden Collection, New York
Fig. 2a Gerrit Dou, Scholar Interrupted at His Writing, ca. 1635, oil on panel, 24.5 x 20 cm, oval, signed, on a piece of paper protruding from the book, “GDov” (GD in ligature). The Leiden Collection, New York, GD-102 [comparison viewer]
Gerrit Dou,  Scholar Interrupted at His Writing, verso,  ca. 1635,  The Leiden Collection, New York
Fig. 2b Gerrit Dou, Scholar Interrupted at His Writing, verso,  ca. 1635,  The Leiden Collection, New York [comparison viewer]
Gerrit Dou,  Portrait of a Young Man with a Hat,  ca. 1635,  The Leiden Collection, New York
Fig. 3a Gerrit Dou, Portrait of a Young Man with a Hat, ca. 1635, oil on panel, 38 x30.5 cm. The Leiden Collection, New York, GD-100 [comparison viewer]
Gerrit Dou,  Portrait of a Young Man with a Hat, verso,  ca. 1635,  The Leiden Collection, New York
Fig. 3b Gerrit Dou, Portrait of a Young Man with a Hat, verso,  ca. 1635,  The Leiden Collection, New York [comparison viewer]
Gerrit Dou,  Portrait of a Lady in Profile,  ca. 1635–40,  The Leiden Collection, New York
Fig. 4a Gerrit Dou, Portrait of a Lady in Profile, ca. 1635–40, oil on panel, oval inlaid into a rectangular panel, 13.3 x 11.3 cm, signed, left center, “GDou” (GD in ligature). The Leiden Collection, New York, GD-110 [comparison viewer]
Gerrit Dou,  Portrait of a Lady in Profile, verso,  ca. 1635–40,  The Leiden Collection, New York
Fig. 4b Gerrit Dou, Portrait of a Lady in Profile, verso,  ca. 1635–40,  The Leiden Collection, New York [comparison viewer]
Gerrit Dou,  Portrait of a Gentleman with a Walking Stick,  ca. 1645,  The Leiden Collection, New York
Fig. 5a Gerrit Dou, Portrait of a Gentleman with a Walking Stick, ca. 1645, oil on panel, 49.2 x 39.7 cm, signed, right, “GDou”(GD in ligature). The Leiden Collection, New York, GD-113 [comparison viewer]
Gerrit Dou,  Portrait of a Gentleman with a Walking Stick, verso, ca. 1645, The Leiden Collection, New York
Fig. 5b Gerrit Dou, Portrait of a Gentleman with a Walking Stick, verso,  ca. 1645,  The Leiden Collection, New York [comparison viewer]
Gerrit Dou,  Portrait of a Lady with a Music Book,  ca. 1640–44,  The Leiden Collection, New York
Fig. 6a Gerrit Dou, Portrait of a Lady with a Music Book, ca. 1640–44, oil on panel, 27.1 x 19.8 cm, signed, on the book, “GDou”(GD in ligature). The Leiden Collection, New York, GD-116 [comparison viewer]
Gerrit Dou,  Portrait of a Lady with a Music Book, verso,  ca. 1640–44,  The Leiden Collection, New York
Fig. 6b Gerrit Dou, Portrait of a Lady with a Music Book, verso,  ca. 1640–44,  The Leiden Collection, New York [comparison viewer]
Gerrit Dou,  Cat Crouching on the Ledge of an Artist’s Atel, 1657,  The Leiden Collection, New York
Fig. 7a Gerrit Dou, Cat Crouching on the Ledge of an Artist’s Atelier, 1657, oil on panel, 34 x 26.7 cm, signed and dated, on the ledge,“GDou 1657”(GD in ligature). The Leiden Collection, New York, GD-108 [comparison viewer]
Gerrit Dou, Cat Crouching on the Ledge of an Artist’s Atelier, verso, 1657, The Leiden Collection, New York
Fig. 7b Gerrit Dou, Cat Crouching on the Ledge of an Artist’s Atelier, verso, 1657,  The Leiden Collection, New York [comparison viewer]
Gerrit Dou,  Portrait of Dirck van Beresteyn,  ca. 1652,  The Leiden Collection, New York
Fig. 8a Gerrit Dou, Portrait of Dirck van Beresteyn, ca. 1652, oil on silver-copper alloy support, oval, 10 x 8 cm, signed, upper right, “GDou”(GD in ligature). The Leiden Collection, New York, GD-111 [comparison viewer]
Gerrit Dou,  Portrait of Dirck van Beresteyn, verso,  ca. 1652,  The Leiden Collection, New York
Fig. 8b Gerrit Dou, Portrait of Dirck van Beresteyn, verso,  ca. 1652,  The Leiden Collection, New York [comparison viewer]
Gerrit Dou,  Young Woman Holding a Parrot,  ca. 1660–65,  The Leiden Collection, New York
Fig. 9a Gerrit Dou, Young Woman Holding a Parrot, ca. 1660–65, oil on panel, 24.8 x18.6 cm. The Leiden Collection, New York, GD-105 [comparison viewer]
Gerrit Dou,  Young Woman Holding a Parrot, verso,  ca. 1660–65,  The Leiden Collection, New York
Fig. 9b Gerrit Dou, Young Woman Holding a Parrot, verso,  ca. 1660–65,  The Leiden Collection, New York [comparison viewer]
Gerrit Dou,  Goat in a Landscape,  ca. 1660–65,  The Leiden Collection, New York
Fig. 10a Gerrit Dou, Goat in a Landscape, ca. 1660–65, oil on panel, 19.5 x24.9 cm, signed, lower center, “GDou” (GD in ligature). The Leiden Collection, New York, GD-114 [comparison viewer]
Gerrit Dou,  Goat in a Landscape, verso,  ca. 1660–65,  The Leiden Collection, New York
Fig. 10b Gerrit Dou, Goat in a Landscape, verso,  ca. 1660–65,  The Leiden Collection, New York [comparison viewer]
Gerrit Dou,  Hermit Praying,  ca. 1665–70,  The Leiden Collection, New York
Fig. 11a Gerrit Dou, Hermit Praying, ca. 1665–70, oil on panel, 18 x 12.9 cm, signed, center right, “GD”(GD in ligature). The Leiden Collection, New York, GD-107 [comparison viewer]
Gerrit Dou,  Hermit Praying, verso,  ca. 1665–70,  The Leiden Collection, New York
Fig. 11b Gerrit Dou, Hermit Praying, verso,  ca. 1665–70,  The Leiden Collection, New York [comparison viewer]
Gerrit Dou,  Old Woman at a Niche by Candlelight, 1671,  The Leiden Collection, New York
Fig. 12a Gerrit Dou, Old Woman at a Niche by Candlelight, 1671, oil on panel, 26.7 x20.8 cm, signed, bottom center, “GDovAnno 1671”(GD in ligature). The Leiden Collection, New York, GD-103 [comparison viewer]
Gerrit Dou,  Old Woman at a Niche by Candlelight, verso, 1671,  The Leiden Collection, New York
Fig. 12b Gerrit Dou, Old Woman at a Niche by Candlelight, verso, 1671,  The Leiden Collection, New York [comparison viewer]
Gerrit Dou,  Herring Seller and a Boy,  ca. 1664,  The Leiden Collection, New York
Fig. 13a Gerrit Dou, Herring Seller and a Boy, ca. 1664, oil on panel, 42.3 x 33.3 cm, signed, bottom center, “GDou”(GD in ligature). The Leiden Collection, New York, GD-106 [comparison viewer]
Gerrit Dou,  Herring Seller and a Boy, verso,  ca. 1664,  The Leiden Collection, New York
Fig. 13b Gerrit Dou, Herring Seller and a Boy, verso,  ca. 1664,  The Leiden Collection, New York [comparison viewer]
Detail of the cloak of the scholar’s proper rig,
Fig. 14 Detail of the cloak of the scholar’s proper right shoulder of Scholar Interrupted at His Writing showing losses that reveal a rust-colored sketch over a light-colored ground and primuersel, field of view: 2.75mm (photomicrograph: John Twilley) [comparison viewer]
Infrared image detail of Scholar Sharpening a Qu,
Fig. 15 Infrared image detail of Scholar Sharpening a Quill showing line underdrawings of the book and hourglass, together with a broader-brushed sketch at the top rim of the book. InGaAs camera using 1500-1680nm filter (image: Shawn Digney-Peer) [comparison viewer]
Infrared image detail of Scholar Interrupted at ,
Fig. 16 Infrared image detail of Scholar Interrupted at His Writing showing underdrawing and modeling around birdcage at the upper center. InGaAs camera using 1500-1680nm filter (image: Shawn Digney-Peer) [comparison viewer]
Detail of Scholar Interrupted at His Writing sh,
Fig. 17a Detail of Scholar Interrupted at His Writing showing visual detail of ear with faint sketch lines, field of view: 11mm (photomicrograph: John Twilley) [comparison viewer]
Infrared image detail of the face, 875-1100nm fil,
Fig. 17b Detail of Scholar Interrupted at His Writing showing infrared image detail of the face, 875-1100nm filter (photomicrograph: John Twilley) [comparison viewer]
Infrared image of Portrait of a Lady with a Musi,
Fig. 18 Infrared image of Portrait of a Lady with a Music Book showing delicate line drawing around the books, as well as vigorous undermodeling of the woman’s outer gown, in the dead coloring phase. InGaAs camera using 1500-1680nm filter (image: Shawn Digney-Peer) [comparison viewer]
Infrared image detail of Portrait of a Lady with,
Fig. 19 Infrared image detail of Portrait of a Lady with a Music Book showing the line underdrawing of the book on the woman’s lap. InGaAs camera using 1500-1680nm filter (image: Shawn Digney-Peer) [comparison viewer]
Infrared image detail of Portrait of a Lady with,
Fig. 20 Infrared image detail of Portrait of a Lady with a Music Book showing the line underdrawings of the books on the table at the far right. In GaAs camera using 1500-1680nm filter (image: Shawn Digney-Peer) [comparison viewer]
Infrared image detail of Hermit Praying showing,
Fig. 21 Infrared image detail of Hermit Praying showing underdrawing of the hands, 800-900nm filter (photograph: John Twilley) [comparison viewer]
Infrared image of Hermit Praying showing vigoro,
Fig. 22 Infrared image of Hermit Praying showing vigorous undermodeling in the cloak and changes along both shoulders, 950-1000nm filter (image: John Twilley) [comparison viewer]
Infrared image of Portrait of a Gentleman with a,
Fig. 23a Infrared image of Portrait of a Gentleman with a Walking Stick showing initial sketch of arched doorway in the background and column with base on the left. InGaAs camera using 1500-1680nm filter (image: Shawn Digney-Peer) [comparison viewer]
Portrait of a Gentleman with a Walking Stick
Fig. 23b Gerrit Dou, Portrait of a Gentleman with a Walking Stick, ca. 1645, oil on panel, 49.2 x 39.7 cm, signed, right, “GDou” (GD in ligature). The Leiden Collection, New York, GD-113 [comparison viewer]
Infrared image detail of Portrait of a Gentleman,
Fig. 24a Infrared image detail of Portrait of a Gentleman with a Walking Stick showing changes in the collar, lapel, or breastplate during the preparatory stage, 1000-1050nm filter (image: Annette Rupprecht) [comparison viewer]
Detail of Portrait of a Gentleman with a Walking Stick
Fig. 24b Gerrit Dou, Portrait of a Gentleman with a Walking Stick, detail, ca. 1645, oil on panel, 49.2 x 39.7 cm, signed, right, “GDou” (GD in ligature). The Leiden Collection, New York, GD-113 [comparison viewer]
Infrared image of Scholar Interrupted at His Wri,
Fig. 25 Infrared image of Scholar Interrupted at His Writing showing broad brushwork in the scholar’s garment and along the front of the table. InGaAs camera using 1500-1680nm filter (image:ShawnDigney-Peer) [comparison viewer]
Infrared image of Scholar Sharpening a Quill sh,
Fig. 26 Infrared image of Scholar Sharpening a Quill showing brushed sketch work of scarf around scholar’s neck and original position of the inkwell. InGaAs camera using 1500-1680nm filter (image: Shawn Digney-Peer) [comparison viewer]
Infrared image detail of Scholar Sharpening a Qu,
Fig. 27a Infrared image detail of Scholar Sharpening a Quill showing the brush sketch in the scarf around the scholar’s neck and the dead coloring around the figure’s proper left hand knuckles. InGaAs camera using 1500-1680nm filter (image: Shawn Digney-Peer) [comparison viewer]
Detail of Scholar Sharpening a Quill
Fig. 27b Gerrit Dou, Scholar Sharpening a Quill, detail, ca. 1630–35, oil on panel, 25 x 20.5 cm, oval, signed, center right, under quill, “GD”(GD in ligature). The Leiden Collection, New York, GD-104 [comparison viewer]
Sample from the cloak of Scholar Sharpening a Qu,
Fig. 28a Sample from the cloak of Scholar Sharpening a Quill showing the violet-brown dead color and upper violet lake layer (a) Cross section in reflected light (the top layer is retained only at the left end), 200x (photomicrograph: John Twilley) [comparison viewer]
Sample from the cloak of Scholar Sharpening a Qu,
Fig. 28b Sample from the cloak of Scholar Sharpening a Quill showing the violet-brown dead color and upper violet lake layer, UV autofluorescence differentiating the two layers, 200x (photomicrograph: John Twilley) [comparison viewer]
Sample from the cloak of Scholar Sharpening a Qu,
Fig. 28c Sample from the cloak of Scholar Sharpening a Quill showing the violet-brown dead color and upper violet lake layer, partially dispersed pigments from both layers showing particles of lake from the top layer and iron earth pigment with Kassel earth from the dead coloring, transmitted light with partially crossed polars, 400x (photomicrograph: John Twilley) [comparison viewer]
Infrared image of Old Woman at a Niche by Candle,
Fig. 29 Infrared image of Old Woman at a Niche by Candlelight showing broadly brushed sketch work in the initial design phase. InGaAs camera using1500-1680nm filter (image: Shawn Digney-Peer) [comparison viewer]
Infrared image of Herring Seller and a Boy, 100,
Fig. 30 Infrared image of Herring Seller and a Boy, 1000-1050nm filter (image: Annette Rupprecht) [comparison viewer]
Infrared image of Young Woman Holding a Parrot, 1000-1050nm filter (image: Annette Rupprecht)
Fig. 31 Infrared image of Young Woman Holding a Parrot, 1000-1050nm filter (image: Annette Rupprecht) [comparison viewer]
Detail of Portrait of Dirck van Beresteyn showi,
Fig. 32 Detail of Portrait of Dirck van Beresteyn showing the fine craquelure in the blue background near the mid-left edge, field of view: 6mm (photomicrograph: John Twilley) [comparison viewer]
Dispersed pigments from Portrait of Dirck van Be,
Fig. 33 Dispersed pigments from Portrait of Dirck van Beresteyn showing dark gray paint containing lead white, boneblack, well-preserved smalt, and isotropic hydrated iron oxide (goethite), transmitted light with partially crossed polars, 400x (photomicrograph: John Twilley) [comparison viewer]
Smalt grainfrom the blue background of Portrait ,
Fig. 34a Smalt grain from the blue background of Portrait of Dirck van Beresteyn (with adhering lead white particles), back scatter electron image, 4,720x (electron micrograph: John Twilley) [comparison viewer]
Elemental composition obtained by X-ray spectrome,
Fig. 34b Elemental composition obtained by X-ray spectrometry during SEM observation. Cobalt in a potash-silica glass is responsible for its blue color. Arsenic detected here is a typical contaminant in cobalt ores used for the coloring of smalt (electron micrograph: John Twilley) [comparison viewer]
Detail of Scholar Interrupted at His Writing sh,
Fig. 35 Detail of Scholar Interrupted at His Writing showing the scarf on the tablecloth emerging from beneath the book where a fine crack disclosed a series of blue layers beneath, field of view: 3.6mm (photomicrograph: John Twilley) [comparison viewer]
Cross section from Scholar Interrupted at His Wr,
Fig. 36a Cross section from Scholar Interrupted at His Writing showing a thin section of the upper layers from the book shadow on the scarf atop the tablecloth, after reduction to 10 microns in thickness, as viewed in transmitted light between crossed polars (photomicrographs and electron micrograph: John Twilley) [comparison viewer]
Cross section from Scholar Interrupted at His Wr,
Fig. 36b Cross section from Scholar Interrupted at His Writing showing the section as viewed using ultraviolet fluorescence microscopy (photomicrographs and electron micrograph: John Twilley) [comparison viewer]
Cross section from Scholar Interrupted at His Wr,
Fig. 36c Cross section from Scholar Interrupted at His Writing showing backscatter electron micrograph showing the dearth of lead white apart from those areas on the left disturbed by lead soap formations from layers beneath. The uppermost layer contains vivianite that has transformed from blue to yellow. Indigo masks the bire fringence of azurite and calcite in the intermediate layers, obscuring distinctions among those layers in transmitted light while they can be differentiated into distinct layers by UV fluorescence microscopy,500x (photomicrographs and electron micrograph: John Twilley) [comparison viewer]
Cross section detail from the scarf over the tabl,
Fig. 37 Cross section detail from the scarf over the tablecloth in Scholar Interrupted at His Writing showing the upper blue strata in the SEM. The low contrast in this backscatter electron image shows the dearth of heavy elements in these layers, including lead white pigment, and implies that they were all intended to be translucent. X-ray spectrometry shows that iron phosphate is common in the top layer (corresponding to the yellow observed in the thin section), and that calcite and gypsum are common in the thicker stratum just beneath. The organic colorant indigo, responsible for blue color in this stratum, is not detectable by this method. Azurite occurs in the lower stratum included in this view, 5,850x (electron micrograph: John Twilley) [comparison viewer]
X-ray spectra from the upper most yellow layer of the scarf in Scholar Interrupted at His Writing (cross hair in Fig. 37) showing a layer composition as a whole, with pigmentation by vivianite and calcite with an ear absence of lead white
Fig. 38a X-ray spectra from the upper most yellow layer of the scarf in Scholar Interrupted at His Writing (cross hair in Fig. 37) showing a layer composition as a whole, with pigmentation by vivianite and calcite with an ear absence of lead white [comparison viewer]
X-ray spectra from the upper most yellow layer of the scarf in Scholar Interrupted at His Writing (cross hair in Fig. 37) showing iron phosphate in individual degraded vivianite particles
Fig. 38b X-ray spectra from the upper most yellow layer of the scarf in Scholar Interrupted at His Writing (cross hair in Fig. 37) showing iron phosphate in individual degraded vivianite particles [comparison viewer]
Partially dispersed pigments from the intermediat,
Fig. 39a Partially dispersed pigments from the intermediate layers from the tablecloth and scarf sequence in Scholar Interrupted at His Writing demonstrating the presence of isotropic indigo along with birefringent calcium carbonate. Polarized light microscopy in transmitted light with polars (photomicrograph: John Twilley) [comparison viewer]
Partially dispersed pigments from the intermediat,
Fig. 39b Partially dispersed pigments from the intermediate layers from the tablecloth and scarf sequence in Scholar Interrupted at His Writing demonstrating the presence of isotropic indigo along with birefringent calcium carbonate. Polarized light microscopy in transmitted light without polars, 1,000x (photomicrograph: John Twilley) [comparison viewer]
Detail of a stripped state photo during treatment,
Fig. 40 Detail of a stripped state photo during treatment of Goat in a Landscape showing losses in the sky along striations of the wood grain at the upper left, revealing the gray dead coloring underneath the uppermost layer of ultramarine (photograph: Nancy Krieg) [comparison viewer]
Cross section of a sample from the sky of Goat i,
Fig. 41a Cross section of a sample from the sky of Goat in a Landscape showing the ground, primuersel, blue-gray dead coloring, and final blue layers, cross section in reflected light (photomicrographs: John Twilley) [comparison viewer]
Cross section of a sample from the sky of Goat i,
Fig. 41b Cross section of a sample from the sky of Goat in a Landscape showing the ground, primuersel, blue-gray dead coloring, and final blue layers, thin section in transmitted light with crossed polars (photomicrographs: John Twilley) [comparison viewer]
Cross section of a sample from the sky of Goat i,
Fig. 41c Cross section of a sample from the sky of Goat in a Landscape showing the ground, primuersel, blue-gray dead coloring, and final blue layers, ultraviolet autofluorescence showing subdivisions in primuersel, 100x (photomicrographs: John Twilley) [comparison viewer]
Dispersed pigments from the sky of Goat in a Lan,
Fig. 42a Dispersed pigments from the sky of Goat in a Landscape showing particles of isotropic natural ultramarine from the uppermost blue stratum that illustrate its great diversity of particle sizes, all in good condition, transmitted light with partially crossed polars, 400x (photomicrographs: John Twilley) [comparison viewer]
Dispersed pigments from the sky of Goat in a Lan,
Fig. 42b Dispersed pigments from the sky of Goat in a Landscape showing particles of isotropic natural ultramarine from the uppermost blue stratum that illustrate its great diversity of particle sizes, all in good condition, transmitted light with partially crossed polars, 400x (photomicrographs: John Twilley) [comparison viewer]
Partially dispersed pigment from the blue-gray de,
Fig. 43 Partially dispersed pigment from the blue-gray dead coloring of the sky of Goat in a Landscape showing fine ultramarine, lead white and black, demonstrating that this was a purposeful blue-gray mixture and not the result of ultramarine degradation, in transmitted light with crossed polars, 400x (photomicrographs: John Twilley) [comparison viewer]
Detail of a leaf in the foreground of Goat in a ,
Fig. 44 Detail of a leaf in the foreground of Goat in a Landscape showing deep blue color and the use of yellow ochre for the vein, field of view: 2.75mm (photomicrograph: John Twilley) [comparison viewer]
Cross section of a sample from the foreground lea,
Fig. 45a Cross section of a sample from the foreground leaf of Goat in a Landscape showing underlying pale yellow application that has been painted out, cross section in darkfield reflected light, 125x (photomicrographs and electron micrograph: John Twilley) [comparison viewer]
Cross section of a sample from the foreground lea,
Fig. 45b Cross section of a sample from the foreground leaf of Goat in a Landscape showing underlying pale yellow application that has been painted out, thin section in transmitted light with crossed polars, 125x (photomicrographs and electron micrograph: John Twilley) [comparison viewer]
Cross section of a sample from the foreground lea,
Fig. 45c Cross section of a sample from the foreground leaf of Goat in a Landscape showing underlying pale yellow application that has been painted out, UV autofluorescence showing yellow-fluorescing lakes, including those in opaque lower layers, 125x (photomicrographs and electron micrograph: John Twilley) [comparison viewer]
Cross section of a sample from the foreground lea,
Fig. 45d Cross section of a sample from the foreground leaf of Goat in a Landscape showing underlying pale yellow application that has been painted out, backscatter electron image showing additional layer differentiation. At least nine layers are present as noted (photomicrographs and electron micrograph: John Twilley) [comparison viewer]
Detail of Herring Seller and a Boy showing mid-tones in the face of the old woman achieved by dark undermodeling, superimposed with translucent flesh tones and additional highlights
Fig. 46 Detail of Herring Seller and a Boy showing mid-tones in the face of the old woman achieved by dark undermodeling, superimposed with translucent flesh tones and additional highlights [comparison viewer]
Detail of Young Woman Holding a Parrot showing the birdcage, an area that represents Dou's working method of painting in sequential planes from the rear to the front
Fig. 47 Detail of Young Woman Holding a Parrot showing the birdcage, an area that represents Dou’s working method of painting in sequential planes from the rear to the front [comparison viewer]
Detail of Scholar Sharpening a Quill showing the brushwork of the proper right hand of the scholar
Fig. 48 Detail of Scholar Sharpening a Quill showing the brushwork of the proper right hand of the scholar [comparison viewer]
Detail of Hermit Praying showing hatching brushwork around the figure’s proper right eye
Fig. 49 Detail of Hermit Praying showing hatching brushwork around the figure’s proper right eye [comparison viewer]
Detail of Hermit Praying showing hatching brushwork along the highlights of the figure’s clenched hands
Fig. 50 Detail of Hermit Praying showing hatching brushwork along the highlights of the figure’s clenched hands [comparison viewer]
Detail of Young Woman Holding a Parrot showing the hatching brushwork along the highlights of the draped curtain
Fig. 51 Detail of Young Woman Holding a Parrot showing the hatching brushwork along the highlights of the draped curtain [comparison viewer]
Detail of Scholar Interrupted at His Writing showing the printed book and handwritten letter in the foreground
Fig. 52 Detail of Scholar Interrupted at His Writing showing the printed book and handwritten letter in the foreground [comparison viewer]
Details of Scholar Interrupted at his Writing s,
Fig. 53a Details of Scholar Interrupted at his Writing showing a “handwritten” text of letter rendered by diluted fine black pigment applied with dithering brushstrokes (photomicrographs: John Twilley) [comparison viewer]
Details of Scholar Interrupted at his Writing s,
Fig. 53b Details of Scholar Interrupted at his Writing showing a “printed” text of the book rendered by thinly dispersed coarse black pigment applied in linear strokes, field of view for both: 2.75mm (photomicrographs: John Twilley) [comparison viewer]
Detail of Scholar Interrupted at His Writing showing the shelf in the background that includes the miniscule letters “…ALVES” on the front of a jar, partially obscured by an overlapping jar
Fig. 54 Detail of Scholar Interrupted at His Writing showing the shelf in the background that includes the miniscule letters “…ALVES” on the front of a jar, partially obscured by an overlapping jar [comparison viewer]
Detail of Goat in a Landscape showing the complex brushwork achieved in rendering the plushness of wavy hair
Fig. 55 Detail of Goat in a Landscape showing the complex brushwork achieved in rendering the plushness of wavy hair [comparison viewer]
Detail of Cat Crouching on the Ledge of an Artist’s Atelier showing the individual bristles and brushstrokes that make up the tabby’s striped pattern
Fig. 56 Detail of Cat Crouching on the Ledge of an Artist’s Atelier showing the individual bristles and brushstrokes that make up the tabby’s striped pattern [comparison viewer]
Detail of Portrait of a Lady in Profile showing individual strands of hair painted in flesh tones that overlay her upper temple
Fig. 57 Detail of Portrait of a Lady in Profile showing individual strands of hair painted in flesh tones that overlay her upper temple [comparison viewer]
Detail of Portrait of a Lady in Profile showing the fur trim painted by dragging the brush back and forth in the adjacent paint
Fig. 58 Detail of Portrait of a Lady in Profile showing the fur trim painted by dragging the brush back and forth in the adjacent paint [comparison viewer]
X-radiograph of Goat in a Landscape showing a change from a profile to frontal view of the goat’s head
Fig. 59a X-radiograph of Goat in a Landscape showing a change from a profile to frontal view of the goat’s head [comparison viewer]
Gerrit Dou, Goat in a Landscape, ca. 1660–65, The Leiden Collection, New York, GD-114
Fig. 59b Gerrit Dou, Goat in a Landscape, ca. 1660–65, oil on panel, 19.5 x24.9 cm, signed, lower center, “GDou” (GD in ligature). The Leiden Collection, New York, GD-114 [comparison viewer]
X-radiograph of Portrait of a Lady with a Music Book showing a change in the arched top and a shift of the figure to the right
Fig. 60a X-radiograph of Portrait of a Lady with a Music Book showing a change in the arched top and a shift of the figure to the right [comparison viewer]
Gerrit Dou, Portrait of a Lady with a Music Book, ca. 1640–44, The Leiden Collection, New York, GD-116
Fig. 60b Gerrit Dou, Portrait of a Lady with a Music Book, ca. 1640–44, oil on panel, 27.1 x 19.8 cm, signed, on the book, “GDou”(GD in ligature). The Leiden Collection, New York, GD-116 [comparison viewer]
Detail of Portrait of a Lady in Profile showing a change in the woman’s upper profile
Fig. 61 Detail of Portrait of a Lady in Profile showing a change in the woman’s upper profile [comparison viewer]
X-radiograph of Old Woman at a Niche by Candlelight showing the original flame of the oil lamp at the center right
Fig. 62a X-radiograph of Old Woman at a Niche by Candlelight showing the original flame of the oil lamp at the center right [comparison viewer]
Gerrit Dou, Old Woman at a Niche by Candlelight, 1671, The Leiden Collection, New York, GD-103
Fig. 62b Gerrit Dou, Old Woman at a Niche by Candlelight, 1671, oil on panel, 26.7 x20.8 cm, signed, bottom center, “GDovAnno 1671”(GD in ligature). The Leiden Collection, New York, GD-103 [comparison viewer]
Stripped-state photo of Old Woman at a Niche by ,
Fig. 63a Stripped-state photo of Old Woman at a Niche by Candlelight (photograph: Nancy Krieg) [comparison viewer]
Detail of a stripped state photo showing the earl,
Fig. 63b Detail of a stripped state photo showing the earlier position of the woman’s proper left arm and hand, which originally rested on the middle of the base of an oil lamp. The original flame of the lamp emerged from the left side of the metal receptacle, where the old woman’s proper left fingers are now located (photograph: Nancy Krieg) [comparison viewer]
Godfried Schalcken,  Conversion of Mary Magdalen, showing a comparabl, 1700,  The Leiden Collection, New York
Fig. 64a Godfried Schalcken, Conversion of Mary Magdalen, signed and dated, lower left: “G. Schalcken/ 1700,”oil on canvas, 94 x 68.6 cm. The Leiden Collection, New York, GS-114, showing a comparable oil lamp with the flame emerging from the side [comparison viewer]
Godfried Schalcken,  Conversion of Mary Magdalen, detail of Conversi, 1700,  The Leiden Collection, New York
Fig. 64b Godfried Schalcken, Conversion of Mary Magdalen, signed and dated, lower left: “G. Schalcken/ 1700,”oil on canvas, 94 x 68.6 cm. The Leiden Collection, New York, GS-114, showing a comparable oil lamp with the flame emerging from the side, detail [comparison viewer]
X-radiograph of Scholar Interrupted at His Writing showing an earlier easel in the background
Fig. 65a X-radiograph of Scholar Interrupted at His Writing showing an earlier easel in the background [comparison viewer]
Gerrit Dou, Scholar Interrupted at His Writing, ca. 1635, The Leiden Collection, New York, GD-102
Fig. 65b Gerrit Dou, Scholar Interrupted at His Writing, ca. 1635, oil on panel, 24.5 x 20 cm, oval, signed, on a piece of paper protruding from the book, “GDov” (GD in ligature). The Leiden Collection, New York, GD-102 [comparison viewer]
Circle of Rembrandt van Rijn, possibly Gerrit Dou,  An Artist in His Studio,  ca. 1630,  The Leiden Collection, New York
Fig. 66 Circle of Rembrandt van Rijn, possibly Gerrit Dou, An Artist in His Studio, ca. 1630, oil on panel, 66.7 x 50.8 cm. The Leiden Collection, New York, GD-112 [comparison viewer]
Detail of Scholar Interrupted at His Writing showing the signature,“GDou,”inserted on a piece of paper on the side of the book.
Fig. 67 Detail of Scholar Interrupted at His Writing showing the signature,“GDou,”inserted on a piece of paper on the side of the book. [comparison viewer]
X-radiograph of Cat Crouching on the Ledge of an Artist’s Atelier
Fig. 68a X-radiograph of Cat Crouching on the Ledge of an Artist’s Atelier [comparison viewer]
X-radiograph superimposed on the visual image,
Fig. 68b Cat Crouching on the Ledge of an Artist’s Atelier, X-radiograph superimposed on the visual image (composite: John Twilley) [comparison viewer]
Infrared image detail showing what appears to be ,
Fig. 69 Infrared image detail showing what appears to be a mousetrap in the lower right corner. InGaAs camera using 1500-1680nm filter (image: Shawn Digney-Peer) [comparison viewer]
Dominicus van Tol,  Boy with a Mousetrap,  ca. 1660–64,  The Leiden Collection, New York
Fig. 70a Dominicus van Tol, Boy with a Mousetrap, ca. 1660–64, oil on panel, 29 x23 cm. The Leiden Collection, New York, DT-100 [comparison viewer]
Dominicus van Tol,  Boy with a Mousetrap, detail,  ca. 1660–64,  The Leiden Collection, New York
Fig. 70b Dominicus van Tol, Boy with a Mousetrap, ca. 1660–64, oil on panel, 29 x23 cm. The Leiden Collection, New York, DT-100, detail [comparison viewer]
Infrared image of Cat Crouching on the Ledge of ,
Fig. 71a Infrared image of Cat Crouching on the Ledge of an Artist’s Atelier showing earlier features such as globe at center left and curtain draped to the left. InGaAs camera using 1500-1680nm filter (image: Shawn Digney-Peer) [comparison viewer]
Infrared image superimposed on X-radiograph with ,
Fig. 71b Infrared image superimposed on X-radiograph with inverted density grayscale, showing earlier drape and architectural details as noted (composite: John Twilley) [comparison viewer]
Panel reverse with bevel indicated by arrows, Cat Crouching on the Ledge of an Artist’s Atelier (photograph: Annette Rupprecht)
Fig. 72a Panel reverse with bevel indicated by arrows, Cat Crouching on the Ledge of an Artist’s Atelier (photograph: Annette Rupprecht) [comparison viewer]
Panel reverse in raking light showing bevel on le,
Fig. 72b Panel reverse in raking light showing bevel on left side only of Cat Crouching on the Ledge of an Artist’s Atelier (photograph: Annette Rupprecht) [comparison viewer]

Footnotes

  1. 1. For an overview of Gerrit Dou’s reputation throughout the centuries, see Arthur K. Wheelock Jr., “Dou’s Reputation,” in Ronni Baer, Gerrit Dou 1613–1675: A Master in the Age of Rembrandt, exh. cat. (Washington, D.C.: National Gallery of Art; London: Dulwich Picture Gallery; The Hague: Royal Cabinet of Paintings Mauritshuis, 2000–2001), 12–24. In the century between the publication of Theopile Thoré’s devastating opinion on Dou in his famous Musées de la Hollande (Paris, 1858–60) and Jan Emmens’s positive reevaluation of Dou in the 1960s, the artist was virtually forgotten. Important studies on Dou since the 1960s include Ronni Baer, “The Paintings of Gerrit Dou (1613–1675)” (PhD diss., New York University, 1990), and the exhibition Gerrit Dou 1613–1675 (see above), curated by Ronni Baer. See esp. pp. 39-42 in this exhibition catalogue, where Baer discusses Dou’s working method.

  2. 2. Luuk Struick van der Loeff and Karin Groen, “Probleem, Overwegingen en Beslissingen bij de Conservatie en Restauratie van het Schilderij door Gerard Dou ‘Jonge Moeder,’ Mauritshuis, 1658, inv.nr. 32,” Centraal Laboratorium Themadag 12 (1987): 40-50. A slightly more elaborate, English version of this article appeared as Luuk Struick van der Loeff and Karin Groen, “The Restoration and Technical Examination of Gerard Dou’s Young Mother in the Mauritshuis,” in ICOM Committee for Conservation: 10th Triennial meeting, Washington, DC, ed. Janet Bridgland (Lawrence, Kansas: Allen Press, 1993), 98–103. In the present article, the English version will be cited.

  3. 3. Struik van der Loeff and Groen, “Restoration,” 100: Dou not only changed the position of the head of the young girl behind the cradle, he also appears to have adjusted the date from 1652/3 to 1658, possibly because the original commission of the painting was abandoned in 1652/3 due to the death of the patron. Dou probably revisited the painting in 1658, just before it was purchased by the Staten van Holland and West-Friesland to be part of the 1660 diplomatic “Dutch gift” to Charles II, king of England.

  4. 4. Struik van der Loeff and Groen, “Restoration,” 102–3. Struick van der Loeff and Groen noted the presence of an astonishing twelve layers of alternating brown and black paint underneath the yellow of the lamp.

  5. 5. Eric Jan Sluijter, De lof der schilderkunst: Over schilderijen van Gerrit Dou (1613–1675) en een traktaat van Philips Angel uit 1642 (Hilversum: Verloren, 1993.

  6. 6. Sluijter, Lof der schilderkunst, 58–71: this combination of a high level of detail and loose brushstrokes was already noted by (near-) contemporary art theorists and biographers. In his Nieuwe Schouburgh (The Hague, 1750), vol. 2, p. 4, Johan van Gool speaks of a “zwierige lossigheit,” and Philips Angel in his Lof der Schilderkonst (Leiden, 1642) of “eyghentlijck,” as well as “los,” which can mean realistic as well as loose. Sluijter further remarks that Karel van Mander used exactly this contrast to describe the work of Lucas van Leyden, Dou’s famous early sixteenth-century predecessor, and suggests that Dou was modeling himself after Lucas’s work, whether he was conscious of it or not.

  7. 7. Friso Lammertse, “Veranderen na verloop van jaren: Over Gerard Dou’s Kwakzalver in Rotterdam en het Zelfportret in Kansas City,” in Album Discipulorum J. R. J. van Asperen de Boer, ed. Peter van den Brink and Liesbeth M. Helmus (Zwolle: Waanders, 1997), 111–20, esp. 116–19. Both works include the later 1667 design of the Blauwe Poort gate. In both cases, it appears that Dou was not reworking an already existing gate, but rather added the entire gate in or after 1667. In the case of the Kansas City Self-Portrait, Dou also added other elements, such as the carpet under his proper right arm, at the same time that he added the gate.

  8. 8. Annetje Boersma, “Dou’s Painting Technique: An Examination of Two Paintings,” in Gerrit Dou 1613–1675, exh. cat. (see note 1 above), 54–63.

  9. 9. Boersma, “Dou’s Painting Technique,” 59: whereas the finely ground ultramarine Dou used for his blue pigment in the Rotterdam Lady at Her Toilet is well preserved, the blues in the curtain, the mother’s skirt, and the cradle blanket in the Mauritshuis Young Mother are now a faded gray. See also Struik van der Loeff and Groen, “Restoration,” 101, who first mention this discoloration of the ultramarine in the Young Mother.

  10. 10. Jørgen Wadum, “Dou Doesn’t Paint, Oh No, He Juggles with His Brush: Gerrit Dou, a Rembrandtesque Fijnschilder,” ArtMatters 1 (2002): 62–77.

  11. 11. For an overview of the paintings by Gerrit Dou in this group, see Arthur K. Wheelock Jr., ed., The Leiden Collection Catalogue (forthcoming; web publication, 2014, www.theleidencollection.com).

  12. 12. For the attribution to Dou of an early painting in this group, Artist at his Easel (GD-112), dated to ca. 1630 (see fig. 66), as well as of Two Old Men Disputing (St. Peter and St)  (GD-101), ca. 1630 (previously attributed to the circle of Rembrandt), and Elderly Man (GD-109), after 1640, another work initially thought to be in the circle of Dou, see Wheelock, The Leiden Collection Catalogue (see note 11 above).

  13. 13. Refer to the Appendix for details of the methods employed. All X-radiographs, IR images, dendrochronological reports, and reports of John Twilley’s analytical work are kept on file at the Leiden Collection.

  14. 14. See Christoph Schölzel, “The Technique of the Leiden Fijnschilders,” in The Leiden Fijnschilders from Dresden, ed. Annegret Laabs, exh. cat. (Dresden: Gemäldegalerie Alte Meister; Leiden: Museum De Lakenhal, 2000–2001), 16–24, esp. 16.

  15. 15. For a discussion of the decline of the oak wood trade with the Baltic, mostly due to Polish-Swedish wars in 1626–29 and 1650–55, see Jo Kirby, “Studio Practice and the Training of Artists,” in Art in the Making: Rembrandt, ed. David Bomford (New Haven: Yale University Press, 2006), 14–26, esp. 23.

  16. 16. Ian Tyers, “Tree-Ring Analysis of Scholar Interrupted at His Writing, GD-102,” unpublished dendrochronological report, November 2010, curatorial files, The Leiden Collection: the tree rings match the Eastern Baltic reference data, and the youngest annual ring dates to 1592. This suggests an earliest possible felling date of 1601 with nine sapwood rings (minimum), and an earliest possible production date of 1603 (adding two years for seasoning and transport); a more likely felling date is 1607 with fifteen sapwood rings (median), and a more likely possible production date is 1609 (adding two years for seasoning and transport). In the following references to dendrochronological reports, only the youngest annual ring will be noted. Ian Tyers, “Tree-Ring Analysis of Portrait of a Lady with a Music Book, GD-116,” unpublished dendrochronological report, November 2010, curatorial files, The Leiden Collection: the tree rings match the Eastern Baltic reference data, and the youngest annual ring dates to 1606, indicating a possible felling date.

  17. 17. Ian Tyers, “Tree-Ring Analysis of Herring Seller and a Boy, GD-106,” unpublished dendrochronological report, November 2010, curatorial files, The Leiden Collection: the tree rings match the German and French reference data, and the youngest annual ring dates to 1637.

  18. 18. Boersma, “Dou’s Painting Technique,” 58.

  19. 19. Ian Tyers, “Tree-Ring Analysis ofScholar Interrupted at His Writing, GD-102” unpublished dendrochronological report, November 2010, curatorial files, The Leiden Collection: the youngest annual ring was formed in1592; Ian Tyers, “Tree-Ring Analysis of Goat in a Landscape, GD-114,” unpublished dendrochronological report, November 2010, curatorial files, The Leiden Collection: the youngest annual ring was formed in 1586, and Ian Tyers, “Tree-Ring Analysis ofCat Crouching on the Ledge of an Artist’s Atelier, GD-108,” unpublished dendrochronological report, November 2010, curatorial files, The Leiden Collection: the youngest annual ring was formed in 1580.

  20. 20. Ian Tyers, “Tree-Ring Analysis of Cat Crouching on the Ledge of an Artist’s Atelier, GD-108,” unpublished dendrochronological report, November 2010, curatorial files, The Leiden Collection. It is important to note that these early dates may also be explained by the small size of the panels. Since small panels do not necessarily contain the whole width of a tree, only older wood from the center of the tree may be included.

  21. 21. Ian Tyers, email communication, July 25, 2013, curatorial files, The Leiden Collection. The first wood sawmill in Leiden, De Ruyter, was most likely built in 1628, close to the Boshuizersluis, and it appears to have been the only one in Leiden during Dou’s lifetime. The authors are grateful to Christiaan Vogelaar, email communication, July 31, 2013, for bringing De Ruyter to our attention; some information can be found on the Heritage website of the city of Leiden. (consulted July 31, 2013). By 1663, this mill was owned by the renowned Leiden carpenter Jan van Ackeren, who had worked on the design of the classicist Loridanshof, and whom Dou would have known personally. See the online Dutch windmill database, (consulted July 31, 2013): Van Ackeren gained permission to move his mill from the Boshuizersluis to the other side of the Haagweg, where transport possibilities were much better. It can be assumed that most Dou panels in the Leiden Collection were cut mechanically, presumably in such a mill, if not at De Ruyter itself.

  22. 22. Kirby, “Studio Practice,” 23: these craftsmen were members of the joiners’ and cabinetmakers’ guild. The administration of the Leiden guild of the joiners has not survived. The authors thank Piet Bakker, email communication, August 12, 2013, who conveyed that, based on his database research, at least 150 joiners and cabinetmakers are listed in Leiden in the seventeenth century.

  23. 23. For a discussion on beveling, see Schölzel, “Technique,” 16–17. See also Ernst van de Wetering, Rembrandt: The Painter at Work, rev. ed. (Amsterdam: Amsterdam University Press, 2009; first ed., 1997), 11.

  24. 24. See Van de Wetering, Painter at Work, 11–12, for the discussion of beveling and the cutting of wood: panels had less tendency to warp when cut in this fashion.

  25. 25. Panel-maker marks are often applied with a branding iron on the reverse of the panel, identifying the panel maker as well as the guild. For a discussion of paintings executed in Antwerp, where it appears to have been quite common to use such marks because of the regulations of the Antwerp guild of St. Luke, see Jørgen Wadum, “Recent Discoveriers on Antwerp Panel Makers’ Marks,” Technologia Artis (1993): 96–100.

  26. 26. Kirby, “Studio Practice,” 23.

  27. 27. Van de Wetering, Painter at Work, 13: the clusters range from the smallest size of ca. 15.5 x 12.7 cm, to the largest size of ca. 123.6 x 89.5 cm. It is only when Rembrandt moved to Amsterdam that he stepped away from the somewhat restricted Leiden panel sizes and started to experiment with canvas and less standard panel sizes.

  28. 28. Schölzel, “Technique,” 24: here, the clusters range from the smallest size of ca. 26 x 20 cm to the largest size of ca. 61 x 45 cm.

  29. 29. Schölzel, “Technique,” 24: note that this size falls into the second category on Van de Wetering’s list (Van de Wetering’s smallest category measures ca. 15.5 x 12 cm). Other panels from the Leiden Collection fall under Schölzel’s categories four are ca. 33 x 26 cm; five, ca. 43 x 34 cm, and six, ca. 61 x 45 cm.

  30. 30. Schölzel, “Technique,” 24: in the first group, Schölzel notes four paintings by Dou and one by Willem van Mieris. He also records one Dou in the third category, two in the fourth, three in the fifth, and one in the last category.

  31. 31. See Ronni Baer, “Portrait of a Woman,” in Gerrit Dou 1613–1675, exh. cat. (see note 1 above), 82-83, no. 10. See also Dominique Surh, “Portrait of a Lady in Profile,” in The Leiden Collection Catalogue (see note 11 above), for her correspondence with Marieke de Winkel regarding clues about the dating based on the sitter’s dress.

  32. 32. Ian Tyers, “Tree-Ring Analysis of Portrait of a Lady in Profile, GD-110,” unpublished dendrochronological report, November 2010, curatorial files, The Leiden Collection. Since the oval panel is firmly set into the larger panel, dendrochronological examination of the oval panel is not possible through traditional means at this time.

  33. 33. See Anja K. Ševčík and Jiří Třeštík, “Doorstep Transactions: Structural and Compositional Transformations on Gerard Dou’s Young Lady on a Balcony,” Bulletin of the National Gallery in Prague 22-23 (2012-13): 23-43 . For a partial list of these unusual constructions in Dou’s oeuvre, see also Ronni Baer, “Of Cats and Dogs: Domestic Pets in Rembrandt and Dou,” in Een Kroniek voor Jeroen Giltaij: Kroniek van het Rembrandthuis (Amsterdam: Rembrandthuis, 2012): 63–69, esp. 66, 67 n 16. For a survey of format changes, including inlaid panels, in the work of Dou’s pupil Frans van Mieris, see Quentin Buvelot and Otto Naumann, “Format Changes in the Work by Frans van Mieris the Elder,” Burlington Magazine 150 (2008): 102–4.

  34. 34. John Twilley, “Scientific Examination of Portrait of Dirck van Beresteyn by Gerrit Dou (GD-111),” unpublished report, dated February 23, 2012, curatorial files, The Leiden Collection. For a recent publication on this painting, see Ronni Baer, “Dou and the Delft Connection: The Portrait of Dirk van Beresteyn,” in Face Book: Studies on Dutch and Flemish Portraiture of the 16th-18th Centuries; Liber Amicorum Presented to Rudolf E. O. Ekkart on the Occasion of His 65th Birthday, ed. Edwin Buijsen, Charles Dumas, and Volker Manuth (Leiden: Primavera Pers, 2012), 279–84.

  35. 35. For a discussion of the possible function of this tiny portrait, see Dominique Surh, “Portrait of Dirck van Beresteyn,” in The Leiden Collection Catalogue (see note 11 above).

  36. 36. Ernst van de Wetering cites a 1676 document preserved in the Leiden municipal archives, which provides an interesting case for suggesting that Leiden artists relied on the services of a single primer. The authors are grateful to Piet Bakker for providing a transcription of the passage (email communication, August 11, 2013) that clarifies the account. It appears that Dirck de Lorme (ca. 1635–ca. 1673) was the ebony worker (ebbenhoutwerker) who held the monopoly for priming canvases and panels in Leiden up until his death, and that Leendeert van Nes made the petition in 1676 to take over this service, rather than the other way around as described by Van de Wetering. See Van de Wetering, Painter at Work, 22 n 29. For other discussions of the ground layer during this period, see also Ashok Roy, “The Ground Layer: Function and Type,” in Art in the Making: Rembrandt, ed. David Bomford (New Haven: Yale University Press, 2006), 27–29, esp. 27; and Melanie Gifford, “Lievens’ Technique: ‘Wonders in Smeared Paint, Varnishes, and Oils,’” in Jan Lievens: A Dutch Master Rediscovered, ed. Arthur K. Wheelock Jr., exh. cat. (Washington, D.C.: National Gallery of Art; Milwaukee Art Museum; Amsterdam: Rembrandthuis, 2008–9), 40–53, esp. 42.

  37. 37. Struik van der Loeff and Groen, “Restoration,” and Boersma, “Dou’s Painting Technique,” 58.

  38. 38. Struik van der Loeff and Groen, “Restoration,” 100.

  39. 39. At the far right side of the Scholar Interrupted at His Writing, the area of the support bar of the globe is thinly painted and lies atop what appears to be the bare wood of the panel, visible through the craquelure. See John Twilley, “Scientific Examination of Scholar Interrupted at His Writing by Gerrit Dou (GD-102),” unpublished report dated April 2011, curatorial files, The Leiden Collection. In a painting from the early 1660s, Goat in a Landscape, the ground structure appears more uniform at the two sample locations taken in the areas of the sky and foliage. The ground layer recovered with both samples was based first upon lead white, followed by a thin tan stratum, rich in earth pigments, probably a primuersel. See John Twilley, “Scientific Examination of Goat in a Landscape by Gerrit Dou (GD-114),” unpublished report dated February 2013, curatorial files, The Leiden Collection.

  40. 40. In the life of Hieronymous Bosch, Karel van Mander describes a primuersel as the transparent layer applied directly over the line underdrawing on top of the ground. Karel Van Mander, Het Schilder-Boeck (Haarlem: Paschier van Wesbysch, 1604), fol. 216v; for an English translation, see Karel van Mander, The Lives of the Illustrious Netherlandish and German Painters, from the First Edition of the ‘Schilder-boeck’ (1603–1604), trans. and ed. Hessel Miedema (Doornspijk: Davaco, 1994).

  41. 41. Wadum, “Dou Doesn’t Paint,’” 66. Wadum does not differentiate between the ground applied by the primer and the upper ground, or the primuersel, applied by the artist, and refers more generally to the ground as being light or buff colored.

  42. 42. John Twilley, “Scientific Examination of Scholar Interrupted at His Writing by Gerrit Dou (GD-102),” unpublished report dated April 2011, curatorial files, The Leiden Collection.

  43. 43. John Twilley, “Scientific Examination of Goat in a Landscape by Gerrit Dou (GD-114),” unpublished report dated February 2013, curatorial files, The Leiden Collection.

  44. 44. Wadum, “Dou doesn’t paint,” 65.

  45. 45. For a list of paintings in which Wadum found partial, or fragmented, underdrawings, see Wadum, “Dou Doesn’t Paint,” 65–66.

  46. 46. While carbon-based underdrawings are virtually absent in Rembrandt’s painting, his own teacher, Pieter Lastman, seems to have executed preparatory underdrawings. An elaborate drawing was found in the infrared photograph of David and Uriah (1619, oil on panel, 41.6 x 62.5 cm; The Leiden Collection, New York, inv. no. PL-100). In this example, Lastman adhered closely to his initial conception and changed only a few minor details during the subsequent painting process, for instance, the position of the head of David’s dog. See Annette Rupprecht,“Technical Notes of David and Uriah by Pieter Lastman, PL-100,” unpublished report dated March 2012, curatorial files, The Leiden Collection, and Rachel Pollack, “David and Uriah by Pieter Lastman,” in The Leiden Collection Catalogue (see note 11 above).

  47. 47. In addition to the possibility of a medium lacking carbon black, another explanation for the appearance of Dou’s “fragmented” underdrawings, could be that subsequent paint layers further obscure them. However, certain examples, such as the Hermit Praying, lack any areas that are obscured by IR-absorbing pigments and yet possess sketch lines prominent in some areas and absent in many others.

  48. 48. The authors are thankful to Dr. Tico Seifert of the National Gallery of Scotland for confirming that similar line underdrawings were found in the window panes, figure, and in isolated areas of the tablecloth in Dou’s earliest dated painting, the 1637 Violin Player (Edinburgh, National Gallery of Scotland), painted within a few years of the Scholar Interrupted, email communication, July 30, 2013. The authors are also grateful to Dr. Seifert for providing X-radiograph and IR photographs for study in July 2013. Groen and Struick van der Loeff indicated that the Young Mother at the Mauritshuis contains a clear underdrawing, most likely in carbon black along the folds of the mother’s skirt. They noted that the lines appear uniform and were drawn as though guided by the straight edge of a ruler. Struik van der Loeff and Groen, “Restoration,” 100–101. The authors would also like to thank Petria Noble of the Royal Cabinet of Paintings Mauritshuis for providing X-radiographs and IR photographs of Dou’s 1658 Young Mother for study in July 2013.

  49. 49. Here, however, the dark hatchings that appear in the IR photograph follow the final result of the paint layer so closely that it cannot be determined with absolute certainty whether the IR photograph reveals an underdrawing, and not the paint layers.

  50. 50. According to Gerard de Lairesse’s Het groot Schilderboeck of 1707, there are four stages in the painting process: “inventing,” the “dead coloring,” the second coloring or “working up,” and the “retouching” or finishing. See Van de Wetering, Painter at Work, 27 n 43; David Bomford, “The Paint Layers,” in Art in the Making: Rembrandt (see note 36 above), 30–34, esp. note 2.

  51. 51. Wadum notes that Dou would “delineate the composition in bluntly applied brush strokes of varying thickness before spreading the undermodeling in monochrome hues.” Wadum, “Dou Doesn’t Paint,” 67. In Rembrandt’s Concord of the State, from ca. 1640 (Rotterdam, Museum Boijmans van Beuningen), an underlying compositional sketch was found, which Van de Wetering cites as an example of Rembrandt’s laying in simultaneously the monochrome dead coloring with a sketch in a “provisionally completed whole.” Van de Wetering, Painter at Work, 27. Thus it seems plausible that Dou may have also handled the sketch phase as synonymous with the dead coloring.

  52. 52. Wadum, “Dou Doesn’t Paint,” 67.

  53. 53. John Twilley, “Scientific Examination of An Old Scholar Sharpening a Quill by Gerrit Dou (GD-104),” unpublished report dated January 2013, curatorial files, The Leiden Collection.

  54. 54. For a discussion about the pigment samples and their cross sections, see John Twilley, “Scientific Examination of Goat in a Landscape by Gerrit Dou (GD-114),” unpublished report dated February 2013, curatorial files, The Leiden Collection. For a general technical overview with notes about its recent conservation history, see Annette Rupprecht, “Technical Notes of Goat in a Landscape by Gerrit Dou, GD-114,” unpublished report dated August 2011, curatorial files, The Leiden Collection.

  55. 55. There was seldom the opportunity to take cross sections for stratigraphic analysis in important areas of the compositions and, accordingly, pigment identifications are more numerous from the uppermost layers or more heavily painted areas. Cross sections were prepared when feasible.

  56. 56. Raman spectroscopy, often highly effective on isolated pigments, is seldom successful on embedded cross sections of dried oil paint. The sample quantities required for chromatographic methods of lake pigment identification were unacceptable for these small paintings.

  57. 57. Lead-fatty acid soaps are the reaction products of lead, derived from lead-based pigments, interacting with free fatty acids, liberated from the drying oils in the medium. Over time, small nodules of these products may erupt from the paint surface, giving rise to minute blemishes that catch and scatter the light. Even when not visible on the paint surface their development was frequently noted during laboratory study.

  58. 58. The alteration of smalt occurs by decomposition of the powdered glass of which it is composed, usually with the loss of the cobalt responsible for its color. The process proceeds from the exterior to the interior of each individual grain so that small particles may be affected throughout, while coarse ones acquire a “rind” from which the color has been lost around an intact core. Neither condition was evident in the samples from this painting, which retain brilliant saturated color throughout a wide range of particle sizes. Discussions of the forms of smalt alteration, its underlying causes and the means of its recognition can be found in the following references: Laurianne Robinet, Marika Spring, and Sandrine Pages-Camagna, “Vibrational Spectroscopy Correlated with Elemental Analysis for the Investigation of Smalt Pigment and Its Alteration in Paintings,” Analytical Methods 5 (2013): 4628–38 http://dx.doi.org/10.1039/c3ay40906f ; Jaap J. Boon et al., “Imaging Microspectroscopic, Secondary Ion Mass Spectrometric and Electron Microscopic Studies on Discoloured and Partially Discoloured Smalt in Cross sections of 16th-Century Paintings,” Chimia 55 (2001): 952–60.

  59. 59. E.-L. Richter, “Seltene Pigmente im Mittelalter,” Zeitschrift für Kunsttechnologie und Konservierung 2 (1988): 171–77; Mark Richter, “Shedding Some New Light on the Blue Pigment ‘Vivianite’ in Technical Documentary Sources of Northern Europe,” ArtMatters 4 (2007): 37–53; H. Stege et al., “Vivianit — Neue Nachweise des Pigmentes und seine charakteristischen Veränderungen in der niederländischen Malerei des 17. Jahrhunderts,” in Archäometrie und Denkmalpflege — Kurzberichte, ed. O. Hahn and H. Stege, (Bochum: Bergbau-Museum Bochum, 2006), 81–83.

  60. 60. Vivianite has long been known to undergo oxidation of its iron accompanied by the breakdown of the crystallinity of the mineral. T. L. Watson, “The Colour Change in Vivianite and Its Effects on the Optical Properties,” American Mineralogist 3 (1918): 159–61; John Twilley, “Polychrome Decorations on Far Eastern Gilt Bronze Sculpture of the Eighth Century,” in Scientific Research on the Sculptural Arts of Asia: Proceedings of the Third Forbes Symposium at the Freer Gallery of Art, eds. Janet G. Douglas, Paul Jett, and John Winter (London: Archetype, 2007), 174–87 (Figures 10a, e, and f in this reference show the dramatic color change associated with the alteration of paint consisting solely of vivianite); J. O. Nriagu, “Stability of Vivianite and Ion-Pair Formation in the System Fe3(PO4)2–H3PO4–H2O,” Geochimica et Cosmochimica Acta 36 (1972): 459–70 http://dx.doi.org/10.1016/0016-7037(72)90035-X ; David A. Scott and Gerhard Eggert, “The Vicissitudes of Vivianite as Pigment and Corrosion Product,” Reviews in Conservation 8 (2007): 3–13. The concept that all iron phosphate pigment occurrences constitute “vivianite” is an oversimplification, since the mineralogical literature describes several related, but distinct, compounds including metavivianite and ferrostrunzite. While these contain some ferric iron and often possess colors ranging from blue to brown, testing by methods capable of distinguishing between these iron phosphates has shown that metavivianite has also been employed in painting and can sometimes retain a blue color. See Hartmut Kutzke et al.,“Alteration of Vivianite Pigments in Paint Layers of 17th-Century Oil Paintings,” ESRF Experiment #ME-1199, March 1, 2006 (http:ftp.esrf.eu/pub/UserReports/32509_A.pdf; accessed, February 3, 2011). The authors cite the occurrence of vivianite in a sample from Dou’s 1646 The Praying Anchorite. While artists of the seventeenth century lacked the means to fully know or control what was in their pigments, we can expect that someone devoting the attention to his work that Dou displays would have been very selective in choosing among these highly variable materials.

  61. 61. Margriet van Eikema Hommes, “Indigo as a Pigment in Oil Painting and Its Fading Problems,” in Changing Pictures: Discoloration in 15th-17th Century Oil Paintings (London: Archetype, 2004).

  62. 62. The pervasive application of such a costly pigment may reflect the preference of the painting’s original owner, Johan de Bye. For a discussion of the painting, its meaning, and early ownership by De Bye, see Dominique Surh, “Goat in a Landscape,” in The Leiden Collection Catalogue (see note 11 above).

  63. 63. John Twilley, “Scientific Examination of Goat in a Landscape by Gerrit Dou (GD-114),” unpublished report dated February 2013, curatorial files, The Leiden Collection.

  64. 64. A“lake” pigment is composed of soluble organic color of the type used in the dyeing of fabric that has been immobilized on a colorless carrier such as chalk, alumina, or gypsum so that it can function as a pigment. Lakes are typically less resistant to light-fading than mineral pigments.

  65. 65. The color saturation of this yellow was low in all places where it occurs, even those beneath opaque layers that could be expected to have sheltered it from fading. These lower layers, which comprise a yellow application covered over by the leaf that was not part of its construction, were not intended to influence the layers above. Differentiation of all strata comprising the foliage sample required the application of all four methods of sample preparation illustrated in figure 39a-d. However, it was impossible to isolate any examples of the yellow lake for other forms of analysis or, often, to differentiate the lake from its neighbors during scanning electron microscopy. No lead-tin yellow or orpiment was found in the yellows. John Twilley, “Scientific Examination of Goat in a Landscape by Gerrit Dou (GD-114),” unpublished report dated February 2013, curatorial files, The Leiden Collection.

  66. 66. For an overview of Rembrandt’s similar working order, which follows a widespread practice in the seventeenth century, see Van de Wetering, Rembrandt: The Painter at Work, 32–44, 45 n 54.

  67. 67. For an example of Dou leaving an area unpainted in reserve, see John Twilley, “Scientific Examination of Cat Crouching on the Ledge of an Artist’s Atelier by Gerrit Dou (GD-108),” unpublished report dated December 2013, curatorial files, The Leiden Collection.

  68. 68. For a detailed account of the sequence of painting in this area as indicated by the overlapping layers of paint, see John Twilley, “Scientific Examination of Young Woman Holding a Parrot by Gerrit Dou (GD-105),” unpublished report dated February 2014, curatorial files, The Leiden Collection.

  69. 69. Baer, “The Paintings of Gerrit Dou,” nos. 113, 116; Baer, Gerrit Dou 1613-1675, 112, 130, 132;Sluijter, Lof der schilderkunst, 58; Wadum, “Dou Doesn’t Paint,” 68–69.

  70. 70. Wadum, “Dou Doesn’t Paint,” 68–69.

  71. 71. John Twilley, “Scientific Examination of Scholar Interrupted at His Writing by Gerrit Dou (GD-102),” unpublished report dated April 2011, curatorial files, The Leiden Collection. It is unclear which word is partially represented; for a fuller discussion of the iconography, see Dominique Surh, “Scholar Interrupted at His Writing” in The Leiden Collection Catalogue (see note 11 above).

  72. 72. The X-radiograph indicates that the rectangular composition was initially conceived as an arched top. The greater visibility of the arch along the upper right-hand side coincides with the direction of the fall of light onto this area and accounts for the greater content of lead white in the underlying paint. Dou seems to have positioned the figure centrally underneath this arch, and when he later added the asymmetrical curtain, he shifted the figure to the right in order to allow for a more even distribution of background space surrounding the woman’s head. See Dominique Surh, “Portrait of a Lady with a Music Book,” in The Leiden Collection Catalogue (see note 11 above).

  73. 73. Annette Rupprecht, “Technical Notes of Old Woman at a Niche by Candlelight by Gerrit Dou, GD-103,” unpublished report dated March 2012, curatorial files, The Leiden Collection, has noted a slightly raised triangular shape near the base of the old woman’s left hand where the artist painted the top of the oil lamp, visible in the X-radiograph, and infrared photograph, as well as in the raking light photograph.

  74. 74. A similar oil lamp is also found in Gerrit Dou’s Old Woman with Two Young Children, ca. 1655, (Boston, Museum of Fine Arts), see Ronni Baer, “A Dou for Boston,” in Collected Opinions: Essays on Netherlandish Art in Honour of Alfred Bader, eds. Volker Manuth and Axel Rüger (London: Paul Holberton, 2004), 18–25, esp. 21.

  75. 75. Baer, “The Paintings of Gerrit Dou,” no. 14; Ronni Baer, “Man Interrupted at His Writing,” in Gerrit Dou 1613–1675, exh. cat. (see note 1 above), 70–71, no. 4.

  76. 76. For an overview of Dou’s depictions of the artist at work, see R. W. Hunnewell, “Gerrit Dou’s Self Portraits and Depictions of the Artist” (PhD diss., Boston University, 1983).

  77. 77. For a discussion of the attribution history of the Artist at His Easel, ca. 1630, oil on panel, 66.7 x 50.8 cm; The Leiden Collection (GD-112), see Dominique Surh, “Artist at His Easel,” in The Leiden Collection Catalogue (see note 11 above). Two other paintings with similar subject matter are illustrated in Gerrit Dou 1613–1675, exh. cat. (see note 1 above), 64–65, no. 1; 68–69, no. 3.

  78. 78. A parasol frequently appears in Dou’s later paintings, particularly in his own self-portraits, in conjunction with an easel in the background; for example, his Self-Portrait of 1647 in the Dresden Gemäldegalerie Alte Meister. A parasol also appears in The Quack in the Boijmans Museum in Rotterdam to highlight the subject, who performs to an audience of gullible listeners. On the parallel between the artist and the quack in working deception, see J. A. Emmens, “De Kwakzalver: Gerrit Dou (1613–1675),” Openbaar Kunstbezit 15 (1971): 4a-b; Ivan Gaskell, “Gerrit Dou, His Patrons and the Art of Painting,” Oxford Art Journal 5, no. 1 (March 1982): 18–20 http://dx.doi.org/10.1093/oxartj/5.1.15 ; and Svetlana Alpers, The Art of Describing (Chicago: University of Chicago Press, 1983), 116–18. It is not clear whether Dou’s inclusion of the parasol in the Scholar Interrupted at His Writing is also a reference to deception.

  79. 79. In his 2002 publication, Jørgum Wadum observed that in an earlier composition the large book in the Scholar Interrupted at His Writing was originally planned to lie flat on the table. Our X-radiograph and IR photograph (at 1500 nanometers) does not indicate any such change in the position of the book, so it remains unclear as to what his comment precisely refers. Nevertheless, his explanation does address some of the otherwise perplexing changes that consist of broad features seen in IR photography in the bottom foreground that have no parallels in the final painting. See Wadum, “Dou Doesn’t Paint,” 69 n 46.

  80. 80. Annette Rupprecht, “Technical Notes of Scholar Interrupted at His Writing by Gerrit Dou, GD-102,” unpublished report dated March 2011, curatorial files, The Leiden Collection.

  81. 81. Baer mentions the possible influence of Rembrandt in his portraits from the early 1630s, where he placed his signature in a letter or paper held by the subject; see Ronni Baer, “Man Interrupted at His Writing,” in Gerrit Dou 1613–1675, exh. cat. (see note 1 above), 70–71, no. 4 n 4, 136.

  82. 82. See Junko Aono, “Boy with a Mousetrap by Candlelight by Dominicus van Tol,” in The Leiden Collection Catalogue (see note 11 above), in which a boy holds a similar mousetrap with a diagonal lever at the top that would have controlled the trapping mechanism.

  83. 83. Baer suggests that the young woman originally belonged to a separate composition and that when she was painted out, the cat and the curtain were painted in. She speculates that the young woman was intended as part of an independent kitchen scene and was shown leaning forward to pour from a jug. For Dou’s earlier treatment of the subject in Kitchen Scene, late 1640s, oil on panel, 41.3 x 30.5 cm; Copenhagen, Statens Museum for Kunst, and The Mousetrap, ca. 1650, signed, oil on panel 47 x 36 cm; Montpellier, Musée Fabre, and Girl with a Cat and Mousetrap (formerly Sotheby’s, London, July 3, 2013, no. 13; now with Adam Williams, New York), see Ronni Baer, “Of Cats and Dogs,” 67–68, 69 n 19, fig. 4.

  84. 84. The image of a cat watching a mousetrap first appeared in Daniel Heinsius’s popular book of love emblems from 1608, Emblemata amatoria, where it symbolized the ensnarement of love, with the weary, trapped mouse representing the love-struck soul and the cat embodying the lust that ultimately does in its prey. Heinsius’s twentieth emblem depicts a mouse inside a wooden trap, too frightened to come out for fear of the lurking cat who keeps watch beside it, while a mischievous Cupid with his bow and arrow iterates the underlying theme of love. Daniel Heinsius, Emblemata Amatoria (Amsterdam, 1608), fol. 20. For a fuller discussion of the iconography, see Dominique Surh, “Cat Crouching on the Ledge of an Artist’s Atelier” in The Leiden Collection Catalogue (see note 11 above.

  85. 85. Neither the ground nor the paint layer itself extends over the edges of the panel. See Annette Rupprecht, “Technical Notes of Cat Crouching on the Ledge of an Artist’s Atelier by Gerrit Dou GD-108,” unpublished report dated March 2012, curatorial files, The Leiden Collection.

  86. 86. Left in reserve, the globe itself appears not to have been painted but merely planned. See John Twilley, “Scientific Examination of Cat Crouching on the Ledge of an Artist’s Atelier by Gerrit Dou (GD-108),” unpublished report dated December 2013, curatorial files, The Leiden Collection.

  87. 87. Cat Crouching on the Ledge of an Artist’s Atelier is unusual in its iconographic simplicity. Baer has observed that the tail of a mouse emerges from underneath the proper left paw of the cat, but this observation appears to be a misreading of an area of exposed ground where two areas of dark paint originally conjoined. See Baer, “Of Cats and Dogs,” 66.

  88. 88. Eric Jan Sluijter, “Venus, Visus, and Pictura,” in Seductress of Sight: Studies in Dutch Art of the Golden Age (Zwolle: Waanders, 2000), 87–159, esp. 90–99.

  89. 89. For a similar interpretation, see Baer, “Of Cats and Dogs,” 66-69. On the wide range of meanings associated with the representation of the cat in the seventeenth century, see Susan Donahue Kuretsky, “Rembrandt’s Cat,” in Aemulatio Imitation: Emulation and Invention in Netherlandish Art from 1500 to 1800; Essays in Honor of Eric Jan Sluijter, ed. Anton W. A. Boschloo, Nicolette C. Sluijter-Seijffert, Jacquelyn N. Coutre, and Stephanie S. Dickey (Zwolle: Waanders, 2011), 263–76.

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DOI: 10.5092/jhna.2014.6.1.3
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Dominique Surh, Ilona van Tuinen, John Twilley, "Insights from Technical Analysis on a Group of Paintings by Gerrit Dou in the Leiden Collection," Journal of Historians of Netherlandish Art 6:1 (Winter 2014) DOI: 10.5092/jhna.2014.6.1.3