Managing Surfactant Leaching in Humid Conditions
Definition: Painting surfactant leaching appears as blotchy, sometimes glossy, tan or brownish spots on the surface of latex paints. Surfactants are a necessary ingredient in making paint. They evaporate and are not part of the paint film; their appearance does not harm it any way. In most cases, the leaching occurs slowly and is washed away by weathering before even being noticed.
CAUSES:
* Painting in cool, humid conditions, or just before or after rain. The longer drying time caused by these conditions allows the paint’s water-soluble ingredients to rise to the surface before the paint thoroughly dries.
* Exposing the freshly painted surface to mist, dew, fog, or other moisture.
PAINTING SURFACTANT LEACHING SOLUTIONS:
* Do not paint if temperatures are below 50º F in the late afternoon and if cool, damp conditions are expected in the evening or overnight.
* If painting surfactant leaching occurs in the first few days after the paint is applied, the blotches or stains can usually be rinsed off with a strong stream of water from a garden hose. A month of normal weathering will remove even stubborn cases of leaching. Painting surfactant leaching does not affect the ultimate durability of the coating.
