WEST SYSTEM 422 BARRIER COAT ADDITIVE – A proprietary blend designed to improve cured epoxy’s moisture exclusion effectiveness. 422 is used as a barrier coating additive to help prevent gelcoat blistering in polyester fiberglass boat bulls. 422 also increases the epoxy’s abrasion resistance. Cures to a light gray color. Sold by the 16 oz. can.
Mix Ratio: Add to mixed resin/hardener at the rate of 15 to 20% by volume or 3 tablespoons per 8 fl. oz. of epoxy. 32 oz. of 422 will modify one B group of epoxy.