The term surfactant leaching is used to describe spots or streaks of sticky brown or colorless material that appears on the surface of freshly applied latex paint. Surfactant leaching is a common paint problem that may occur with any brand of latex paint. The spots or streaks caused by surfactant leaching, while unsightly, are not harmful and do not affect the performance of the paint.
Surfactants are ingredients in paint that are critical to the performance properties of the paint such as its color, stability, flow, and leveling. These materials usually evaporate in good drying conditions, or they are locked into the paint film. The staining occurs when drying conditions cause the paint to dry too slowly, allowing the surfactants to rise to the surface of the paint. The spotting and streaking occur when moisture condenses on the fresh paint and draws the surfactants rapidly out of the paint film. Heavy condensation will cause streaking from the run down of surfactant-rich water.
Surfactant leaching usually occurs during the spring and fall when the daytime temperatures drop below the dew point rapidly, or when temperatures are low and humidity remains high. In coastal areas, such as San Francisco, the marine layer can suddenly increase humidity and cause surfactant leaching any time of the year.
Surfactant streaking can be washed off but one should be careful not to damage the fresh paint finish while doing so. If left alone, the streaking and discoloration will disappear after a first good rain.