422 Barrier Coat Additive
While WEST SYSTEM Epoxy creates an excellent moisture barrier by itself, 422 Barrier Coat Additive is a proprietary blend designed to further improve cured epoxy’s moisture exclusion effectiveness. 422 is used as a barrier coating additive to help prevent gelcoat blistering in polyester fiberglass boats. 422 also increases the epoxy’s abrasion resistance. Cures to a light gray color.
Add to mixed resin/hardener at the rate of 15 to 20% by volume or 3 tablespoons per 8 fl oz of epoxy. When using 300 Mini Pumps with 5:1 ratio epoxy mixtures, 10 strokes of 105 Resin and 10 strokes of 205 or 206 Hardener yields 8 fl oz. of epoxy; for 3:1 ratio epoxy mixtures, 9 strokes of 105 Resin and 9 strokes of 207 or 209 Hardener yields 8.1 fl oz. of epoxy.
A 16 oz can of 422 Barrier Coat Additive will modify approximately half a gallon of mixed epoxy.