Four - Paints & coatings

Abstract

This chapter focuses on paints and coatings, which are typically classified according to functionality or end-use applications. Functionally, coatings fall into three basic categories: sealers, primers, and top coats. A sealer is a clear or lightly pigmented base coat designed to inhibit capillary action in a porous substrate, such as masonry or wood. Sealers provide a uniform base for the primer, allowing an even film to form, and prevent the migration of extractives from the substrate into the primer and top coats. The primer is considered the first coat, and it ensures the adhesion of the coating system to the substrate to assist in the protection of the substrate and to provide a uniform base for the top coats. The top coats are the finish coats that provide the final protective barrier and present an aesthetically appealing decorative effect. Architectural coatings are essentially the paints used to protect and decorate the exterior and interior of buildings. They are also called “trade sales paints” when sold through retail outlets. These coatings are most often applied to wood and drywall to control moisture absorption, swelling, and degradation, while providing a durable, flexible, and decorative film. Interior and exterior paints are available in both oil- and water-based formulations yielding a flat, semi-gloss, or gloss finish. Industrial coatings are usually applied to ferrous or non-ferrous metal surfaces. Exposed ferrous surfaces oxidize rapidly, forming a non-protective oxide coating.