AbstractThe variation of water absorption with temperature of three varnish films, a pentaerythritol alkyd, an epoxy‐polyamide and a phenol‐formaldehyde tung oil, has been measured. In the case of the first two, minima were observed the temperatures of which corresponded to glass transition temperatures of the polymers. In contrast, films of the phenol‐formaldehyde tung oil varnish showed neither a minimum in the water absorption‐temperature curve nor a glass transition temperature over the range 5–34°C. Further work is necessary to establish whether this relationship has general a