This phenomenon is known by several names: streak staining, surfactant leaching, surfactant staining, exudation and weeping. It can occur with any exterior acrylic /latex house paint when conditions are such that water soluble components of the paint are extracted and deposited in concentration on the surface it is visually more apparent with dark, ultra deep and accent colours.
It can be more problematic with white and light colours, especially if the exudates has a tan colour, as sometimes happens. The likelihood and severity of this deposition of water soluble components depend on the paint formulation and the conditions under which the paint is applied and dried.
All latex paints are made with some water soluble ingredients such as:
All of these ingredients eventually come out of the paint upon exposure. It is normally due to rain and dew, usually during the first several weeks of exposure.
Because of the weather, a large proportion of water soluble ingredients are brought to the surface as the paint dries or shortly thereafter and appear typically as shiny streaks or blotches.
Dew or light rain soon after painting can extract water-soluble, resulting in surfactant leaching.
Surfactant Leaching will generally weather off in a month or so. Removing it before then can be difficult, especially if it has been baked by sunshine.
Care should be taken in trying to remove it with power washing, a paint job remain tender until it has thoroughly dried out or “cured”
For this reason paint companies or sales representatives may suggest the customer to not take action to have the problem area repainted and instead ask the customer to wait, to allow “self-correction” of the problem.
In general, surfactant leaching does not adversely affect the film integrity or exterior durability of the paint.