Acrylic Primer 121 is a general purpose, water based primer and waterproofer designed for application over a wide range of substrates to improve adhesion of topcoats and to control absorption. Acrylic Primer 121 is suitable for use under most water based paints, waterproofing membranes and architectural coatings. It can be applied to almost any surface including masonry, concrete, FC sheet, aluminium, timber, steel, and some plastics.