The capabilities and limitations of Fourier transform infrared spectroscopy for the identification of natural resins used in historic furniture finishes is explored. Fourier transform infrared analysis can identify 5 natural resins (shellac, sandarac, mastic, copal and rosin) individually and as components in a mixture. Varnish preparation and photochemical ageing do not diminish the banc identification scheme. The experimental methods are described. Tables. 16 references.