Cool Weather Coating Application
by Rick Fiderius


With the change in seasons and colder weather comes job-site conditions that can greatly influence a successful deck coating or below-grade membrane application. One such condition is the thickening effect cold weather may have on the viscosity of the liquid coating.

Applicators may try to remedy this by reducing or thinning the material with solvent. While this practice for the most part is not condoned, it none-the-less does occur.

If the wrong choice in solvent is made, the results can be devastating. Solvents that contain alcohol are the worst. Moisture cure polyurethane waterproofing membranes and coatings are severely affected in the uncured state by contact with alcohols. The alcohol will react with the reactive curing-sites of the urethane molecule and completely and permanently prevent any crosslinking conversion (cure) into the desired rubbery material. This phenomenon is industry wide and pertains to all moisture cure polyurethanes on the market.

Some grades of gasoline now contain up to 10 percent 'gasohol' which is ethyl alcohol. It must never be used as a thinner.

While Tremco does not promote job-site thinning of material, Xylene would be the only safe solvent to use if used in limited quantities. Note however that the local VOC regulations will often prohibit this practice.

Therefore, the best recommendation is to follow the guidelines relating to minimum application temperatures in published directions, and to store the material at room temperature heated conditions.