Treasures of Biloxi: Art Conservation in the Wake of Hurricane Katrina

The portrait of Winnie Davis before being treated at Winterthur.

The portrait of Winnie Davis before being treated at Winterthur.

To correct the warping of the canvas, conservation student Kristen de Ghetaldi placed small tabs along the perimeter of the canvas and pulled them slightly every day for several days to eventually achieve an overall evenness of the canvas. The painting was also kept for six hours in a humidification chamber before the inpainting (painting in the areas where there had been paint loss) could begin. Davis's portrait is now fully conserved and restored.

La Bella

Purchased in Europe and brought to Mississippi by Varina Davis, wife of Jefferson Davis, in 1870, La Bella possibly reminded Mrs. Davis of her young daughter Winnie. But the history of the painting's origin is unclear. It depicts a woman wearing a 16th-century gown and an angelic smile. She carries an air of mystery, looking out with eyes both knowing and innocent—and for the WUDPAC conservators the portrait was indeed mysterious. At first glance it appears to be a slightly larger version of the original La Bella, painted in the 16th-century studio of Palma Vecchio that presently hangs in the Thyssen Museum in Madrid. But for the conservators it was not clear whether the one from Beauvoir was made in the same 16th-century studio or was copied later. To properly conserve the painting, a primary part of their work was to determine the date of La Bella's creation.

Since painters' pigments have changed over the years, a common method of dating paintings uses chemical analysis to identify the elements in the pigments. Matching up the elements used in the painting with those known to have been used during certain periods in art history will provide clues to the date of origin. The conservators used ultraviolet scans of La Bella to identify the areas that were left untouched by previous restoration; this is possible because restored areas appear dark under an ultraviolet light. They then subjected 20-µm segments of the unrestored areas of the painting to X-ray fluorescence (XRF) spectroscopy to identify the chemical makeup of the pigments. XRF spectroscopy is a nondestructive technique that allows researchers to identify the elements in a particular pigment by the characteristic secondary X-rays emitted from a sample. As X-rays bombard an object, inner-shell electrons are ejected from atoms. Outer-shell electrons then fill the vacancies that are left in the inner shell and emit their excess energy as secondary X-rays. The characteristic peaks of the fluorescent X-rays identify the elements present; the peaks' height indicates the elements' relative quantities.

With their knowledge of the history of European painting, the conservators had some idea of what to expect from the results of the XRF spectroscopy. Analysis was done on the red, blue, and green areas of La Bella, the predominant colors in the figure's robe. All of the colors showed evidence of lead, which was used in white primer coats of paint before titanium white was first marketed in the 1920s. Having found lead in the primer coat, conservators could date the painting to a range from the 1500s to 1870, when it was purchased.

There were several possible types of pigment that conservators might find in the red paint. Starting in the 14th century European painters often used mercury-rich vermilion for pigment, and many painters still use vermilion today. In the 1500s organic red pigments made from ground female cochineal beetles came to Europe from the Americas. This red color results from carminic acid, produced by the beetles as a protective substance. Chromium red was first used in the early 1800s. Since La Bella was bought in 1870, the conservators were able to rule out the possibility of detecting cadmium, which painters began using in the 1920s. In the final analysis the red pigment showed mercury, and so the conservators were able to identify vermilion red. But since vermilion red has been used continually since the 1300s, the red was not helpful in narrowing the date of the painting.