Elastomeric paints can stretch up to 300% of their original size and then return safely from that point. This allows the coating to expand and contract with the wood. A quality paint manufacturer will test the paint's elasticity at the thickness it recommends it be applied.
Fully cured elastomreic paint is 4 to 5 times thicker than other types of paint. The difference between the thickness of wet paint and dry paint is directly related to the percentage of solids in the paint, which are what is left when the paint has fully dried or cured. High quality paints are 40% to 50% solids. Before painting, refer to the manufacturer's recommended wet film thickness and apply the paint at that thickness.
While elastomeric paints seal out water, they must also allow the wood to breathe or transmit vapors so that they do not become trapped, which can cause peeling or blistering For coating a deck, choose a paint that allows high levels of vapor to pass through it rather than one that is intended to act as a vapor barrier.
According to the Paint Quality Institute, manufacturers choose not to produce elastomeric paint in darker shades because the properties that enable its elasticity and durability also cause darker colors to lighten or fade faster than other paints when exposed to sunlight. If a darker color is a requirement, acrylic paint can be applied on top of the elastomeric. For decks, however, this can lead to the lighter elastomeric paint showing through and will require re-coating sooner.