Preparation - Peeling

Moisture

The maximum moisture content for any surface that is to be painted is 12-14%. Painting a surface that contains a higher level of moisture can lead to peeling problems. The only accurate way of determining moisture content is with an electronic moisture meter.

Too Many Coats

There is a limit to the number of coats of paint that a surface can support. As the paint thickness builds up over time, and the coatings get older, they lose their flexibility. As the substrate (surface) expands and contracts because of temperature fluctuations or moisture, the paint film is no longer flexible enough to move with the surface. Cracking or flaking of the coating usually results. It is not uncommon to put a coat of paint on a surface that appears sound only to have many layers of paint peel away. At this point the surface must be stripped.

Efflorescence

Efflorescence is a white deposit that forms on masonry surfaces. Moisture moving through masonry will pick up water-soluble salts which are left behind when the moisture reaches the other side. The moisture moving through the masonry can pass through a flat paint, but the efflorescence builds up behind the paint until it causes peeling. To solve the problem, the moisture migration must be stopped first and the efflorescence brushed off, before repainting is done.