Partially hydrolyzed poly(vinyl acetate)-borax-based gel-like materials for conservation of art: Characterization and applications

A versatile gel-like system for the treatment of art has been prepared from partially hydrolyzed poly(vinyl acetate), borax, and large fractions of ethanol, isopropyl alcohol, n-propyl alcohol, and acetone. Variables such as the concentrations of the two gelating components, the degree of hydrolysis and molecular weight of the polymer, and the type of liquid gelated were investigated to establish formulations of gels with physical and chemical properties that are best suited for specific applications. The gels were designed to have an elastic character that allows them to conform to the topography of complex surfaces and be removed with ease by being lifted from the surface. Results from fluorescence studies demonstrated that the solvent is constrained within the area of the gel, allowing for localized treatment. Polymer and boron residues were not detected after cleaning tests on acrylic and dammar test paint-outs, and on two oil paintings with degraded surface coatings. The efficacy of the cleaning systems was determined visually. Studies of the materials removed during treatments showed that the gels appear to act by softening the coating surface while typically a pass with a solvent-dampened swab after gel treatment removes the softened coating. Two case studies and notes on other applications of the gels are described; recipes and preparation procedures are included.