Unlocking an Old Master

The conservation of Orazio Gentileschi’s painting of Danaë uncovered the aesthetic power that defines this masterpiece. The problematic condition of the painting, coupled with the deterioration of the materials used in a former treatment, obscured the chiaroscuro and crispness typically found in Gentileschi’s works. During the process, technical analysis and imaging by visiting conservation scientists expanded our knowledge of the materials and techniques used in the painting.  

The treatment was lengthy due to the painting’s scale (63.8 x 90 inches), the number of sizable old losses, the overpaint that covered extensive abrasion of the brown background, and the vast amount of inpainting required. Old retouches and varnish had deteriorated, muddying the careful balance of the original color tonalities, as well as the contrast between light and shadow. Cleaning revealed disfiguring losses, but also the startling splendor of the original paint layers.

Once all the old restoration and varnish were removed, the vital process of filling losses and texturing fills began. Fills needed to mimic Gentileschi’s application of ground and paint layers. Silicon molds, fine knives, and dental tools were employed to imitate the texture of cracked, aged paint. Inpainting simulated the opacity of original brushstrokes and matched the colors, inevitably changed with time.

The entire composition regained its balance and depth as cracks and abrasions throughout the painting were painstakingly retouched using a tiny brush under magnification. This was particularly noticeable in the flesh of Danaë, where a darkened network of cracks and sizable old losses marred the body’s subtle modeling. Danaë’s badly damaged hair was reconstructed using the tiny islands of original paint to establish the color and details of curls.

Treatment revealed the artist’s trademark virtuosity in modeling flesh and drapery. The folds of the white sheet became bold and crisp once again. The fall of light on the figure of Danaë was regained, illuminating the three-dimensionality of her limbs, with masterful mixtures of yellow, pink highlights, and orange-tinted shadows blended to create naturalistic hues. The glints of yellow highlights on the curtain fringe came alive, displaying Gentileschi’s extraordinary skill with small brushes loaded with thick paint.

Image

MA-XRF Image Mapped with RGB The RGB (red/green/blue) process associates each color with a specific element: red = copper, green = zinc, and lead = blue. Those colors represent each element when found by itself, such as the dominance of lead in the white pigment in the figure and sheet. In this image, only copper and zinc are found co-localized in some areas of the green curtain (yellow areas) and would most likely correspond to traces of zinc stemming from the copper-based pigment production process. Image by M. Vermeulen and M. Walton, Center for Scientific Studies in the Arts, Northwestern University

Cross Section Taken from Danaë’s Left Shoulder in Normal Light Two preparation layers are seen under the flesh tone. A red layer was applied before the brown layer, which was used to influence the shadow tones. The flesh pigment in the highlights is primarily lead white. Image by M. Vermeulen and M. Walton, Center for Scientific Studies in the Arts, Northwestern University

To understand the materials and methods used by Gentileschi, the paintings in the upcoming exhibition Variations: The Reuse of Models in Paintings by Orazio and Artemisia Gentileschi underwent technical examination. X-rays revealed his thrifty penchant for creating canvases from patchworked remnants of fabric. Infrared images showed changes and adjustments in the compositions. Digital overlays of related paintings highlighted his use of outlines to copy compositions. Magnification and raking light uncovered his use of incisions to place outlines of figures and facial features.

The strategic plan for the CMA’s Conservation Department has prioritized hiring a conservation scientist. In the meantime, experts from Northwestern University analyzed the layering and pigments used in Danaë. Like many of his Italian contemporaries, Gentileschi employed two layers of colored ground before applying the paint layers. Cross sections of various areas confirm the use of a double ground throughout the painting. Danaë’s upper ground layer is composed of elements found in clay, along with lead white and yellow iron oxide inclusions. The lower red layer contains lead, vermilion, and red iron oxide. The paint is comparatively thin, usually applied in a single layer. For example, shadows in the figure of Danaë are not transparent glazes (composed of a thin application of oil paint) over the flesh tone. Rather they are a different combination of pigments softly blended from shadow into the highlights.

Pigments identified include lead white throughout the figure, and earth colors (iron oxides) in the yellow bedframe, the brown background, the yellow/green coverlet near the foot of the bed, and the drapery around Danaë’s hips. A copper-based green is found in the background curtain, and vermilion imparts vibrancy throughout the highlights and shadows of the red bed cover. Lead-tin yellow (type II) features in the shadows of the figure, the coins, the green cover behind the figure, and the yellow bedframe. The use of this pigment is significant as it was most widely employed between the 1200s and 1700s, falling out of use around 1750. Lead-tin yellow was produced by heating a powder mixture of lead oxide and tin oxide to about 900°C. In type II, the mixture also contained quartz. Its hue is a rich saturated yellow.

Mapping elements using macro X-ray fluorescence (MA-XRF) clarified the distribution of colors and forms, particularly in the green curtain, which had become less legible due to the deterioration of the copper-containing pigment. The scientists also created overlapping MA-XRF images to see where two or three of the elements in the painting coincide, and where pigments can be found singly or mixed together. The lighter flesh tones are primarily lead white, with traces of lead-tin yellow (type II) and hematite, a red iron oxide.

While the pigments identified are commonly found in paintings of this period, it is Gentileschi’s talent for mixing and juxtaposing them, along with his ability to smoothly blend shadow and light, that resonates. The composition is striking in its dynamic pose. Through this extensive treatment and technical analysis, the painterly genius of the artist was unveiled and can once again be fully appreciated.   

Cleveland Art, Winter 2021