Peeling paint is probably one of the most common problems faced by anyone who paints and describes the phenomenon where the paint falls off in small or large dry flakes. The surface, which is supposed to be protected, is then exposed to weather, wind and other destructive forces.
The causes of flaking can be many:
- Surface contamination (grease, oil, wax, etc.)
- Poor adhesion
- Paint not compatible with substrate, primer and/or previous coating
- Insufficient substrate preparation
- Too short or long curing time between coats
- Paint is applied at too high a temperature
Paint adheres to the substrate by drawing into microscopic pores and anchoring. If the pores are too small (i.e. the substrate is too smooth) or clogged with contaminants, water or sealants, the paint will not adhere, will simply dry as a separate layer on top of the substrate and will fall off when it is hit or the substrate moves. If the paint layer cracks or has small holes, water can penetrate underneath and loosen the paint. This is what happened in the example below: Poor adhesion allowed water to penetrate and collect in a bag. It got bigger and bigger, until everything finally came loose. The metal will then corrode and the wood will rot.
Like most challenges, flaking can be prevented with good preparation. You can read how to do this here in our ABC of painting .
