Additives

421 Fire Retardant Additive

421 is a fine white powder added to epoxy in the ratio of 1:1 by weight. It is used to make the cured material fire retardant which is why it is often used in marine applications in engine and galley areas. This additive will, however, greatly increase the viscosity of the epoxy which means that the composition requires trowelling or squeegeeing into place.