Troubleshooting: Cracking/Flaking
- Alligatoring
DESCRIPTION
Alligatoring is a form of paint failure where large cracks form through the surface layer only, resulting in the appearance of an alligator hide.
POSSIBLE CAUSES
- Applying paint over a porous, unsealed surface resulting in rapid absorption and improper film formation.
- Applying paint in high heat or very low humidity causing solvent to evaporate too rapidly.
- Applying second coat of paint before first coat has completely dried.
- Application of a harder, less flexible paint or coating over a softer or more flexible one (a brittle oil-based paint over a more flexible latex paint).
SOLUTION
Remove all loose paint, sand edges smooth, then prime and seal the surface with an appropriate primer for the specific application or surface to be painted. Once primer is completely dry, apply fresh coat of paint.
- Blocking
DESCRIPTION
The unwanted sticking together of two painted surfaces when they are pressed together (such as a door sticking to the door jamb or a window sash sticking to the frame), or a painted surface sticking to another surface such as weather stripping.
POSSIBLE CAUSES
- Insufficient dry time of the paint before closing doors or windows.
- Use of a low quality semi-gloss or gloss paint.
SOLUTION
Apply a top quality semi-gloss or gloss latex paint, preferably one with an acrylic resin. Low quality latex paints will have poor block resistance, especially in hot, humid conditions.
Follow label instructions regarding dry time of the paint. Acrylic latex paint generally has better early block resistance than vinyl latex or alkyd (oil-based) paints, although alkyd paints do develop better block resistance over time. The application of talcum powder, petroleum jelly, or wax can relieve persistent blocking of the paint.
- Flaking
DESCRIPTION
Lifting of paint from the underlying surface in the form of flakes. It is normally preceded by cracking or checking, and can occur over different surfaces.
POSSIBLE CAUSES
- Cracking of exterior wood or plywood as it expands and contracts in response to changes in temperature and humidity, which is transmitted through the paint.
- Poor paint penetration, especially on wood with an excessive amount of hard/flat-grain pattern, which is smooth, hard and nonporous.
- Poor surface preparation.
- Applying the paint too thinly.
SOLUTION
Scrape, sand or use a wire brush to remove loose, peeling paint. Sand rough edges smooth. If necessary, sand to fresh wood, particularly if there are loose wood fibers on the surface or on the back of the paint flakes. Prime the surface with the appropriate primer as soon as the surface has been prepped and is completely dry, then apply fresh paint according to package directions.
- Mudcracking
DESCRIPTION
Deep/irregular cracks dried in the paint film, resembling dried mud.
POSSIBLE CAUSES
- Paint was applied too heavily.
- Paint build-up in corners (walls, ceiling area, etc.).
- Incorrect cleaning, leaving contaminants on the surface before painting.
SOLUTION
Remove all loose paint, sand rough edges, prime if needed, then repaint at recommended spread rate. Determine correct roller cover nap for the surface being coated (1/4" - 3/8" nap for smooth surfaces, 1/2" - 3/4" nap for medium/rough surface, and 1" nap and greater for rougher surfaces).
