clearcoat

Clearcoat is a transparent protective top layer applied over a basecoat in automotive and other painted finishes. Its primary function is to protect the underlying color from UV radiation, moisture, and chemicals while enhancing gloss and perceived depth. Most clearcoats are 2-component polyurethane systems, and they can be solvent-borne or waterborne; some modern variants are UV-curable.

Chemistries typically involve a resin that crosslinks with an isocyanate hardener to form a hard, durable film. Aliphatic polyurethanes are favored for their UV stability and reduced yellowing. Clearcoats are designed to be thin film layers, commonly around 30–60 micrometers, and are used over basecoat pigments or metallics.

Application usually occurs in controlled paint booths: spray-applied onto a cured basecoat, then allowed to dry and cure, sometimes with baking. UV-curable or infrared-assisted systems cure faster and may require specialized equipment. The topcoat can be polished after curing to remove minor imperfections.

Benefits include high gloss, color depth, improved resistance to moisture and chemicals, and easier maintenance. Clearcoats also protect metallic or pearlescent pigments and can help maintain color uniformity across panels.

Issues include yellowing or hazing from UV exposure, solvent pop, shrinking, orange-peel texture, or delamination if surface preparation is inadequate. Re-clearcoating or repainting may be needed after damage, and ongoing maintenance involves regular cleaning and occasional polishing.

Environmental considerations focus on VOC limits for solvent-borne formulas and the push toward waterborne and UV-curable systems, with appropriate safety and waste handling in place.