With the ever changing temperatures we have been experiencing I thought it would be a good time to discuss the effects cool temperature has on paint. First you can get "surfactant leaching" which is when the wetting agents of the paint create a soapy discoloration on the paint films surface. This occurs when applying paint in cool temperatures or very high humidity, or exposing the paint film to these conditions before it is completely dry. This condition can usually be fixed by washing the surface with a mild detergent. Second you can get an uneven sheen when applying paint below 50 degrees, although many exterior paints are now formulated to handle 40 degrees, be careful. The only cure for this is to repaint. The last and most common problem with fluctuating temperature is touch-up difficulties. This happens because paint color changes when it is applied at different temperatures. Cooler paint is lighter than warmer paint. Touch up must be done when the surface, air & paint are of similar temperature as when originally painted.