Deep, irregular cracks that resemble dried mud form in dry paint film.

What Causes It?
Mud cracking occurs when:

• Paint is applied too thickly, usually over a porous surface.
• Paint is applied too thickly to improve inherent poor hiding (coverage) of lower-quality paint.
• Paint is allowed to build up in corners during application.

How to Solve It
To repair mud cracking, first remove the coating by scraping and sanding. Apply primer and repaint, using
a quality latex paint.

Mud-cracked areas can also be repaired by sanding the surface smooth before repainting with a top-quality latex paint. This type of paint is likely to prevent the reoccurence of mud cracking, because it is relatively more flexible than alkyd paint, oil-based paint, and ordinary latex paint.

Quality paints have a higher solids content, which reduces the tendency to mud crack.

They also have very good application and hiding properties, which minimize the tendency to apply too thick a coat of paint.

Note: Images provided by The Rohm & Hass Paint Quality Institute.