Foaming / Cratering
Foaming refers to the tiny bubbles that may form in the paint film during the application process. As the paint dries, these bubbles may break and leave small depressions, known as cratering.
- Shaking a partially filled can of paint.
- Using a low-quality paint or very old water-based paints.
- Applying paint too rapidly, especially with a roller.
- Using a roller cover with the incorrect nap length.
- Excessive rolling or brushing of the paint.
- Applying a gloss or satin paint over a porous surface.
All paints will foam to some degree during application. However, higher-quality paints are formulated to ensure that the bubbles break while the paint is still wet, allowing for good flow and appearance.
Avoid excessive rolling or brushing when applying paint, or using paint that is more than a year old. Apply gloss and satin paints with a short nap roller, and always apply an appropriate sealer or primer before using these paints on a porous surface. Problem areas should be sanded before repainting.