Permafil® 3255 is a clear liquid unsaturated polyester resin which cures to a tough, rigid, infusible solid when catalyzed. Permafil® 3255 is a clear liquid unsaturated polyester resin which cures to a tough, rigid, infusible solid when catalyzed. Its low viscosity permits complete penetration of porous structure and being 100% solid helps eliminate the potential problem of voids which can occur with conventional solvent-borne varnishes.