How does air trapped in a coating typically manifest?

Air trapped in a coating usually manifests as craters or pinholes. This occurs because as the coating dries or cures, the air pockets may expand or seek to escape, leading to the formation of these defects. Craters are depressions that can form when the trapped air escapes during curing, creating a noticeable surface imperfection. Similarly, pinholes are tiny holes left in the coating where air or solvent has escaped, compromising the integrity and appearance of the finish.

In contrast, a smooth finish signifies even application without defects, while a glossy surface refers to the appearance of the coating rather than the presence of defects caused by trapped air. Blistering, while related to air, generally occurs when moisture or air vapor is trapped beneath the coating film, leading to larger defects rather than the small, discrete issues presented by craters or pinholes. Therefore, the manifestation of trapped air is most accurately described by the presence of craters or pinholes in the coating surface.