Elastomeric paint is a special type of paint that is designed with polymers and acrylics in a special combination created for outdoor use, especially use on materials that do not generally hold paint well like stone or concrete. These materials tend to expand and contract as the seasons change, which chips and flakes most paints. Elastomeric paints, however, expand and contract as well, allowing the coat to remain unchanged. Painters should be aware of several problems associated with these paints, especially if they are not applied correctly.
One of the key requirements with elastomeric painting is preparation beforehand. The materials painted with elastomeric coatings are generally susceptible to cracks and fractures. The paint will not solve these problems. Once stone or concrete is cracked, the crack has a habit of breaking apart paint coatings over time as well. To prevent this, painters should always carefully seal any cracks and wait for the sealant to cure before starting to apply the paint.
Elastomeric paints have different moisture sealant qualities. A paint with a strong moisture barrier may be suitable for a very dry climate, but most elastomeric paints should include breathability, a high moisture transference rating. If the paint stops moisture too well, it will collect behind the paint and start to erode the materials or leak down and potentially cause drainage problems.
Designed for adhesion to flat surfaces that are neither porous nor very chalky, one problem that painters encounter with elastomeric paints is a high level of dirt and contaminants on the surface they want to paint. These contaminants must be fully scoured off, or over time they will cause the paint to peel. The elastomeric material will still stretch, but it cannot adhere to the surface properly with contaminants in the way.
With very specific curing conditions, if painters do not match final dry films with set film thickness, the coat may peel with elastomeric paints. The paint must fully cure for at least a year before painters apply a layer of any other paint, and solvent-based paints can never be used. Also, if the surface has too high of a pH level (higher than 9), the mixture will not cure properly.