Household Paint Tips: How To Remove Surfactant Leaching

Article detailing what surfactant leaching is, how to remove it, and how one can prevent it.

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, also known as water spotting, 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.

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. 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, typically on exterior siding. Water condensing overhead can form spots or blotchy areas, typically on a freshly painted bathroom ceiling. There are other causes of surfactant leaching in addition to poor drying conditions. Additional causes are pressure washing that forces moisture into the wall, not allowing one coat of pain to dry before applying another, painting in unheated interiors where the pain is slow to dry, and over application or heavy coats of paint used to achieve a dramatic color change.

Removing surfactant leaching is usually quite easy. If the problem occurs within a day or two of painting, a wet cloth will usually take the spotting and streaking right off, or if outdoors, a gentle spraying with the hose will work. If a simple rinsing is unsuccessful, wait a day or two for the paint film to harden. Then, gently wash the area with a sponge and cool water, being mindful not to damage the new paint. If that doesn't work, a mild dish detergent mixed with water should remove the staining. Assuming a dish detergent didn't work, applying a small amount of a multi-purpose cleaner to the area may do the trick. If you're still not successful, and the surfaces are exposed to weather, you may need to do nothing at all. Weathering will usually remove the staining within a few months.

If the spotting is not exposed to weather and all cleaning options have been exhausted, allow the area to dry completely for two to four weeks. Then, choose a time when slow drying, condensation, and rain spotting will not occur and repaint the entire surface. Repainting so quickly will probably not be an enjoyable experience, being mindful of the situations that contribute to surfactant leaching can help you avoid it this time around.

Surfactant leaching can be avoided if you take the proper care in applying paint and drying the surface. Prevention is the name of the game! Avoid painting in the late afternoon, particularly in the spring and fall, but any time when humidity is high when condensation may occur. Also, avoid painting when rainfall or misting is certain. Consider the use of an oil-based paint if you live in a humid area and avoiding these conditions is not possible.

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