Low Toxicity Solvent Compositions for Varnishes Formulations for Use in Art Conservation

Varnishes consist basically of a resin and solvent. Aromatic solvents are widely used for varnish formulations, but they present considerable toxicity which requires their replacement. Two binary solvent systems with an oxygenated solvent (ethyl acetate or isoamyl acetate) and cyclohexane were studied as possible substitutes for xylene in varnish formulations. The toxicity of solvents was analyzed using data from the Globally Harmonized System of Classification and Labeling of Chemicals and the National Institute for Occupational Safety and Health. The solubility of Damar, Paraloid B72, Regalrez 1094, and Laropal K80 resins in these solvents was evaluated by Hansen and Teas Solubility Parameters, sigma profiles, and experimental method. Vapor pressure measurements were obtained from solvents and viscosity and gloss measurements from varnish formulations. The results indicated the potential of binary solvent systems as substitutes for xylene, but require further studies on their effects on pictorial materials on which they are applied.