Research on conservation materials at the National Gallery of Art has focused on coating materials, such as paints for retouching, coatings for the protection of outdoor bronzes, and varnishes for paintings. In this research, modern synthetic materials are tested for their use in conservation applications, often as replacements for traditional materials, which may be based on unstable natural products. Extensive use is being made of the expertise and materials available from the chemical industry. The materials are tested using accelerated aging methods. Stabilizing additives may be used to prolong the useful life of the materials. An array of analytical methods is being used to monitor changes during aging, and finally conservators judge the products for handling and appearance.