Blog @ the Nelson-Atkins

Senior Conservator Kate Garland recently completed a project cleaning a 10th-century Persian earthenware Platter with Kufic Inscription. Garland noted that the platter appeared to have many fills as well as several areas where overpainting was done by a 20th-century restorer to conceal old breaks.

The platter was cleaned with acetone solvent to remove as much of the dirt and overpaint as was safely possible. As she slowly cleaned, using a wooden stick and cotton tip soaked in the acetone, Garland pointed to areas around the platter’s edges where restorers added paint over the original glaze.

Much of this paint was removed by the cotton tip and acetone, along with dirt. Occasionally, a small scalpel was needed to scrape away tough dirt or paint. Because of the significant risk of damaging art in the process of cleaning (especially during scraping), a cautious and experienced hand is necessary to determine how much pressure to use. The platter’s original colors—made of liquid-colored clays called “slips”—cannot be removed with acetone because they are fired under the original glaze. These colors appeared as Garland cleaned the platter’s rim.

The photo to the left shows a blank spot on the platter’s rim where Garland rubbed and scraped away all of the overpaint. Revealed is what appears to be red clay, which Garland believes is part of the original platter. Reddish-colored clay is also visible on the bottom of the platter (pictured below) in areas where portions of the original glaze have chipped away.

The platter has some cracks and fills that are visible to the naked eye, especially on the bottom where white portions of clay (the fills) can easily be found. However, these cracks and fills are more dramatic when seen on an x-ray (below). X-rays often surprise conservators because they show details that are not evident on the object’s surface. Cracks, fills, and even a “healthier” condition can all be revealed.

Though Garland hoped that all of the pieces seen in the x-ray were portions of the original platter and not added by restorers—and, based on the clean breaks and closely matched portions on the exterior, it seemed possible that the original pieces are all present—on the interior of the platter are jagged edges that suggest areas where restorers added fills.

Acetone solvents can be useful in removing fills, but, unfortunately, on this platter an epoxy may have been used, which meant that platter fragments and fills could not be removed without causing damage. There is a strong possibility that removal of a piece, even if softened by acetone or some other material, will break off another, original fragment or result in original glaze loss. Further complicating matters is the knowledge that some of the glaze loss could look, on the x-ray, like fragments or cracks. As a result, some questions about the condition of the platter will likely go unanswered.

However, there are instances when ingenuity has trumped seemingly irreversible materials. Garland referenced an experiment recently conducted by Senior Associate Conservator Paul Benson: in an attempt to safely soften and remove several layers of materials used to restore a bowl, Benson created two vapor-chambers—one chamber to remove one type of restoration material, a second for other materials. He left fragments sealed (with kitchen tinfoil and plastic wrap) in the chambers for several days and then gauged the progress.

A similar chamber-system would probably not have been effective on Garland’s platter, so her focus shifted to adding fills to broken areas and repainting. This took a substantial amount of time and required, like most projects, many conversations between conservator and curator to determine specific details, such as how much painting should be done and where.

The paint materials that conservators use have been tested and shown to resist discoloration. And they are easily reversible. Among the paints used are premade artist’s acrylics as well as dry color pigments, including mica powder colored by metal (the same type used in car paint), and watercolors. The dry pigments are mixed using an acrylic resin in a solvent. Colors vary greatly, and time and patience is needed to create a mixture that best matches the original.

One of Garland's favorite experiences as a conservator is seeing an object on display, knowing that she added fills or overpaint to it, and being unable to locate those areas because all details are so seamlessly integrated.

For information about other conservation projects, click here or visit the Conservation webpage.

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