Work is reported under three headings. (1) Microsections of paint samples. Paint fragments are mounted in a coldsetting synthetic resin (Marco 26C) which is then ground down to the cross-section. Chemical analysis is carried out both on the cross-section and on an unmounted fragment.(2) Chromatography of natural resins. Fresh natural resins used in varnishes can readily be distinguished using a reversed-phase system of paper chromatography. Resins more than a few years old are, however, oxidised so as to appear as a single spot on the chromatogram in each case. (3) Diffusion phenomena in films.