STOPGAP P131 is a primer designed to promote the adhesion of STOPGAP smoothing underlayments to smooth non-absorbent surfaces. It can also be used as a general purpose primer for absorbent surfaces to promote adhesion and to prevent unacceptably rapid drying of adhesives and smoothing underlayments. It is suitable for use in marine applications as part of an IMO system. It is suitable for use over normal underfloor heating installations. STOPGAP P131 is coloured green to provide the user with visual control of coverage uniformity. STOPGAP P131 should be used on non-absorbent surfaces of STOPGAP waterproof surface membranes, terrazzo, power floated concrete, quarry and ceramic tiles, sound asphalt, epoxy marine primers, well bonded epoxy and polyurethane coatings and minimal existing adhesive residue. It should also be used on absorbent surfaces such as concrete, sand/cement screeds, plywood, hardboard and chipboard.