The Problem: This film discoloration appears as blotchy, tan or brownish spots on the surface of latex paints. Some spots may have a glossy or soapy appearance, and mostly occur in rooms that have high humidity such as bathrooms and kitchens. Discoloration is the result of surfactants (a necessary ingredient in the production of paint) leaching from the topcoat.
Causes: Can include painting in cool humid conditions or painting with dark colored paints requiring large quantities of colorant. Exposing a freshly painted surface to mist, dew, or other forms of moisture can also lead to the leaching of paint surfactants.
How-to-fix: Do not paint in conditions where the temperature is below 50° F or late in the day when damp, cool conditions are expected overnight. If leaching occurs within a few days after the paint is applied, the stains can usually be rinsed off with soap and water. When applying paint in a bathroom, it’s important to allow the topcoat to completely dry and cure before using the shower. Surfactant leaching on exterior surfaces usually diminishes after a month of normal weathering.