Painting Stucco: What Is a Fog Coat?
When painting stucco, the temperature must be between 40 degrees and 90 degrees for optimum results. Since this is not always possible, a fog coat is applied to the finished surface of the stucco in order to give an even appearance in color, while still giving the stucco the ability to evaporate water from inside. This coat is very thin and has no sand mixed in, so it adds no new texture to the stucco. It is used when the weather is colder or hotter than the recommended temperatures for application, or if the humidity is very high which will not allow the stucco to dry properly.