Formation of bubbles (foaming) and the resulting small, round concave depressions (cratering) when bubbles break in a paint film, during paint application and drying.
Shaking a partially filled can of paint
Use of low quality paint or very old latex paint
Applying (especially rolling) paint too rapidly
Use of a roller cover with wrong nap length
Excessive rolling or brushing of the paint
Incorrect application equipment (e.g. Applying a gloss or semi-gloss paint with a long nap roller)
All paints will foam to some degree during application; however, higher quality paints are formulated so the bubbles break while the paint is still wet, allowing for good flow and appearance. Avoid excessive rolling or brushing of the paint. Apply gloss and semi-gloss paints with a short nap roller.
Yellowing describes the development of a yellow cast in ageing paint solvent-based enamels.
Wrinkling is a term to describe a rough, crinkled paint surface, which occurs when uncured paint forms a 'skin'.
Sagging is the downward "drooping" movement of the paint film immediately after application that results in an uneven coating.