What is a topcoat?

A topcoat is final finishing coat of paint, varnish, clear coat, or protective layer applied over primer, undercoat, base coat, or color coat to provide color, gloss, durability, and protection. In house painting, topcoat is final paint layer that gives true color and sheen, such as satin, semi-gloss, or gloss, and is washable and resistant to wear, applied after primer and undercoat, typically two coats for best coverage. For example, interior wall topcoat is latex paint that you see. In woodworking, topcoat is protective clear finish like polyurethane, varnish, or lacquer applied over stain or paint to protect wood and add sheen. In automotive painting, topcoat can mean base color coat plus clear coat, or clear coat itself that provides gloss and UV protection over color. In nail care, topcoat is clear polish applied over color polish to add shine and prevent chipping. In clothing, topcoat is long overcoat worn over suit in cold weather. So generally topcoat means final outer layer that provides appearance and protection, as opposed to primer or undercoat which are base layers. Topcoat is essential for durability and final look.