Cracking

Definition

Splitting of the paint film through at least one coat, leading to failure of the paint. Hairline cracks appear initially, but progress to paint chips falling off the surface – or flaking – and severe cracks in the surface will appear. Complete failure of the paint can occur if left untreated.

Causes

• Over-thinning of the paint or spreading it too thin
• Poor surface preparation, especially when paint is applied to bare wood without priming
• Painting under cool or windy conditions where the paint dries too fast
• On surfaces that have been painted many times, the bottom layers of paint lose their flexibility and are unable to expand and contract with the surface as it responds to temperature and humidity change

Solutions

Determine if cracking goes all the way to the surface.

If cracking does not go all the way down to the surface, then:

• Remove loose and flaking paint with a scraper or wire brush.
• Sand the area and feather the edges.
• Repaint, using a high-quality paint.

If cracking does go to the surface:

• Remove all of the paint by scraping, sanding and/or use paint remover.
• Prime wood and masonry surfaces with an appropriate, high-quality primer.
• Repaint using a high-quality paint

Tips

• If the cracking occurs over plywood, only periodic scraping, repriming and recoating will solve the problem. Latex paints fill plywood cracks better than oil-based paints.
• Pressed composition boards should be primed immediately after installation. An adequate coating should be kept on the surface at all times to seal out moisture.