CAUSE: All latex paints contain detergent-like materials called surfactants which are necessary for the stability of the paint formulation. In cases where surfactant is leaching from the dried film, this material will dissipate in small amounts. They tend to come out of the film slowly and are easily removed by normal weathering. Under certain curing conditions, such as low temperatures, condensing moisture, etc., this leaching process occurs rapidly and results in a surfactant build-up on the surface. Leached surfactant can appear as a thick brown syrup-like deposit or rundown. On occasion it may assume a white crystalline form. Surfactant leaching is not limited to exterior coatings - it may appear in bathrooms or other areas where moisture condenses on walls. In these instances, a clear amber glossy rundown will be visible.

SOLUTION: Most often, weathering removes the visible film of surfactant from the surface. The sheen and the color are restored. However, most accumulations of surfactant are observed in areas protected from natural weathering. In these instances, it can be removed with a fine mist from a garden hose or by light rubbing with a wet cloth. Often the best solution is to do nothing and let nature take its course. The surfactant will do no harm and time will correct the problem.

Above article reprinted by the kind permission of Benjamin Moore Paints.