The long-term stability of a popular heat-seal adhesive for the conservation of painted cultural objects

A large number of products, both natural and synthetic, have been and are used for the consolidation of flaking or fragile paint layers occurring on paintings, polychrome sculpture, furniture and other cultural objects. Most products in use, which include natural as well as synthetic materials, remain untested. Most synthetic materials used for consolidation of paint layers consist of a solution or dispersion of a single polymeric component, and may not have the correct physical and mechanical properties, as they have not been formulated using knowledge and expertise from the field of adhesion science. The only material that has been specifically formulated as an adhesive for the conservation field is BEVA® 371, which contains several components. It was designed as a hot-melt adhesive for the lining of canvas paintings in the early 1970s, but has since then become a popular adhesive for paint layers in need of consolidation. Its stability, an important parameter for this application, was however never fully investigated. This paper investigates the photo-chemical stability of BEVA® 371 as a whole, and each of its components independently using Fourier transform infrared spectroscopy, size exclusion chromatography and solubility tests.