An overview of the results of the research on picture varnishes at The Metropolitan Museum of Art is presented. In order for synthetic varnishes to have optical properties equivalent to those of natural resin varnishes they should have low molecular weight, and a relatively high refractive index. The molecular composition is of minor importance as long as varnishes of low polarity are used. In order for varnishes to be less susceptible to autoxidation reactions, certain chemical groups such as ketone groups and carbon-carbon double bonds should be absent from their molecular structures. Although the low molecular weight varnishes presently available are very brittle, more flexible resins with low molecular weight are feasible. The process by which dammar varnishes, as well as varnishes in general degrade, is predominantly photochemical autoxidation. Yellowing of dammar is a secondary non-oxidative thermal process. Accelerated aging studies should therefore be carried out under light. Polymer stabilizers have the potential to prolong the useful lives of varnishes. Dammar may, however, be very difficult to stabilize. Care should be taken with the use of stabilizing additives since they may have negative side effects. They should not be used without thorough testing. Several new resins are under investigation at the Metropolitan Museum of Art: a derivative of ketone resin was synthesized with improved stability and flexibility; several commercially available resins with high refractive indices, low molecular weights, and solubility in solvents of low polarity are being tested. Solvents for varnishes with low evaporation rates and varying concentrations of aromatics are described. -- AATA