SURFACTANT LEACHING IN EXTERIOR LATEX PAINTS
The issue of surfactant leaching can also be known as streak staining, weeping, exudation, surfactant staining, and other similar names. This is known to occur with exterior latex paints when the environmental conditions cause the water-soluble components of the paint to be extracted and concentrated in deposits on the paint surface. Surfactant leaching is more readily apparent visually with accent colors, especially deep and dark colors, but it can also happen with light colors and whites, especially with tans and beiges. Both the formulation of the paint and the conditions in which the paint is applied and dried directly affect the likelihood of this happening and the severity of the effects.
All latex paints include ingredients that will eventually come out of the paint film when exposed, such as glycols, thickeners, surfactants, dispersants, wetting agents, and others.
Environmental moisture, including rain and dew, will generally leach out these materials in the first few weeks of exposure. Prevailing weather conditions can cause a majority of water-soluble ingredients to come to the surface as the paint dries, or soon thereafter, and these usually manifest as blotches or shiny streaks. Light rain and dew can also result in the extraction of water soluble substances, also known as surfactant leaching, if they occur soon after painting.
The negative visual effects of surfactant leaching will usually be weathered off after about a month of normal exposure in exterior environments, but removal before this period can be very difficult, especially if sunshine has baked the streaks or blotches into the paint surface. Power washing must be undertaken with special care, as new paint can be tender or easily damaged before it has fully cured or dried out.
Therefore, Harris & Ruth Painting suggests that our clients take no action to have such exterior services repainted or cleaned because the problem should fix itself in time. Surfactant leaching generally does not affect the paint’s integrity or durability adversely.
At Harris & Ruth, we strive to formulate our latex paints with as little of these water-soluble substances present as possible, which will help keep this leaching to a minimum. Although universal tinting colorants contain glycols and surfactants, we do our best to achieve good color acceptance, good paint stability, positive application properties, and good film formation to ensure our clients receive the best looking results possible with minimal surfactant leaching.