 All About Surfactant Leaching (and what to do...) What Are Surfactants? Surfactants (surface active agents) are a necessary component of latex house paint. Surfactants are soap compounds that impart color and package stability to the paint. Surfactants contain water-soluble solid matter that migrates from the paint film over time and deposits itself on the surface of the paint. The rate of migration is dependant on weather conditions. Surfactant migration normally occurs over a period of weeks after the paint has been applied. When this happens the deposits formed are microscopic and distributed uniformly over the entire surface. They are not visible. What is Surfactant Leaching? In the spring and fall, temperatures often drop below the dew point at night and condensation forms on exterior surfaces. When condensation forms on a freshly painted surface, the moisture rapidly extracts surfactant from the paint film. When the condensation dries, concentrated surfactants are deposited on the painted surface. They are distinctly noticeable as different in color from the paint. On horizontal siding high concentrations of surfactant tend to run to the bottom edges and accumulate there. This phenomenon is called surfactant leaching. Surfactant leaching is an inconvenience caused by Mother Nature -- not a paint defect. Paint performance is not impacted. Surfactant leaching looks like spots, streaks or blotchiness on the paint. They may be brownish on light colors and whitish on dark colors. Dark colors contain more surfactant and are more prone to surfactant leaching. Rain on fresh paint can also cause surfactant leaching. How Do I Get Rid of It? Surfactant deposits are water-soluble but will harden with time. Within a day or two of application they are still soft and can usually be removed by gently rinsing them off the painted surface with a garden hose. If this does not work, allow the paint to cure for a week and then wash the surfactant off with a soft brush and a mild solution of detergent in water. Rinse thoroughly afterward. If more time has elapsed, additional elbow grease will be required to scrub the surfactant deposits off. Use plenty of water. Dry scrubbing will damage the paint. The amount of surfactant in the paint is minimal but a little more may leach out of the paint after the initial washing. If so, hose it off as soon as it appears. If too much time has elapsed, the surfactant may have hardened to the point where it cannot be removed without damaging the paint. Flat dark paints can be easily marred by even slight abrasion. It is more difficult to remove surfactant deposits from flat dark colors without damaging the appearance of the paint. If the surfactant cannot be removed without damaging the paint, touching up or repainting over the surfactant is required. What Can I Do to Avoid Surfactant Leaching? Never paint outside when rain is imminent. Try to do outside painting during summer months. If you must paint outside in spring or fall, stop painting in the early afternoon. Apply only one coat per day and don’t apply it too heavy. Less paint and more dry time before condensation sets in lower the potential for surfactant leaching. |
