The removal and replacement of varnish on paintings play an important part in their conservation. Proper identification of the varnish type makes removal much more efficient and often reduces the possibility of damage to the painting. In addition, knowledge of varnish types provides important information about artist and workshop methods. Methods of sampling and identification of resinous and synthetic varnish have been developed. Standard spectra using infrared (IR) spectrophotometry in the range of 4000 cm _-1 to 200 cm _-1 have been recorded for the following: Acryloid B-67 and B-72, Gloss Polymer Medium; poly(vinyl acetate) (AYAA and AYAC); Ketone Resin N; Soluvar Matte and Glosses 1 and 2; Copal Painting Medium; dammar; shellacs, white and orange; oils, linseed, stand, and poppy; gum Arabic; and appropriate solvents such as high and low molecular weight alcohols, terpenes, benzene derivatives and petroleum distillates. Characteristic absorption peaks in the spectra are identified and assigned to known structure. Each individual varnish has a unique spectrum. Discussion includes details of experiment, the method for obtaining samples and the results of this study. An example of the identification of an unknown varnish from a painting is presented.