Foaming or cratering is the formation of bubbles and resulting small, round concave depressions in a paint film, during paint application and drying.
Several things can cause foaming or cratering:
- Shaking a partially filled can of paint.
- Use of low quality paint or very old latex paint.
- Use of a roller cover with wrong nap length.
- Excessive rolling or brushing of the paint.
- Applying a gloss or semi-gloss paint with a long nap roller.
All paints will foam to some degree during application; however, quality paints are formulated so the bubbles break while the paint is still wet, resulting in good flow and appearance. Use a quality synthetic roller sleeve (5mm nap for gloss & semi gloss and 12mm nap for low sheen and flat finish).
More problem solving advice
Yellowing is the development of a yellow cast in aging solvent-based enamels. It’s most noticeable in the dried films of white paints or clear varnishes. For each problem you’ll find a guide to identifying it, its causes and solutions.
Have you noticed small droplets appearing on your fresh coat of acrylic paint? This is known as 'surfactant leaching'. Don't panic - it's a normal part of the curing process. For each problem you’ll find a guide to identifying it, its causes and solutions.