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18th-century Iranian shield. The specific features
of its manufacture, conservation and restoration This 18th-century painted shield from Iran is one of the most interesting examples of ceremonial shields in the collection of the State Hermitage. The shield is made of thick buffalo hide (0.6 cm). The central umbo and brackets are made of silver with a gold amalgam. The reinforcement on the reverse side is made of leather and dark blue velvet. The face of the shield is decorated with vegetable ornamentation that is traced in gold. When it was brought in to the Laboratory for Scientific Restoration of Works of Applied Art Made from Organic Materials (T.A. Baranova, director) in 2004, the painting on its front side was in a deplorable state. On the entire surface, the pigment layer had a fine web of cracks (craquelure) with raised edges and was peeling in many places. The biggest loss of the pigment layer (partly down to the primer, partly to the foundation material) was concentrated on the pictures against a black background - four medallions and two bands along the edge of the shield and around the umbo. The thick, yellowed and fragile lacquer layer had losses through to the pigment layer. The entire surface was covered in dirt. In the Department of Scientific and Technical Expertise headed by A.I. Kosolapov, a preliminary examination was made of the shield, and this helped to determine the make-up of the pigments in the paint layer. During investigation of the black colour, the presence of cobalt, arsenic and potassium was discovered. The silvery-coloured stratum lying under areas of black paint is a layer of tin without binding matter. Metallic dowels in the midst of the leather, covered with painting on the front side, consist of low-zinc brass. The functional significance of the dowels could not be explained. Analysis makes it possible to suggest the presence of smalt and, very likely, the original colour of what are now black areas of painting was dark blue, which would contrast well with two-coloured gold. The tin substrate created an additional effect of "luminescence" of the blue colour. Precisely the presence of tin between layers of the prime coating and the paint explains the considerable losses of the paint layer with lacquer on the four medallions. The fact is that when there were variations in temperature and humidity, the coefficients of contraction of the tin layer and the paint layer were different, and this led to the tearing away of the layers on top. In those areas where there was no tin substrate, the painted surface has less peelings and losses. The state of preservation of the item required that urgent conservation work be carried out. It was necessary to strengthen the remaining pigment layer. Moreover, the Restoration Commission proposed that the lost parts be filled in and that the painted surface be tinted. Conservation and restoration of the paint layer was carried out using a methodology close to the one used to restore painted art works on wood. The pigment layer of the front side was strengthened with a 3% solution of sturgeon-based glue and honey. The raised areas of craquelure were smoothed down using cigarette paper and a teflon-coated flat surface. The surface dirt was removed using a 3% solution of children's soap. Losses of the pigment layer were filled in with a resin made of chalk and a 4% solution of sturgeon glue and honey tinted using watercolours. The tinting of the main field of the shield (excluding the areas at the edge with considerable losses) was done while reconstructing the vegetable ornamentation according to surviving samples. Following the restoration work, the surface of the shield was covered with a protective film. |
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Hermitage Museum |
