Surfactant leaching: Blotchy usually tan colored glossy water soluble spots on latex paints.
Leaching probable causes: Painting in cool humid conditions or just prior to their occurrence, such as late afternoon or just before or just after rain. If moisture from any source collects on fresh paint before it has thoroughly dried, leaching may occur.
Leaching solutions: No painting if temperatures are below 50°F or late PM when it’s cooler. Coolness extends drying. Surfactants that usually evaporate, rise to the surface. The residue disappears from weathering in about a month and doesn’t harm the paint. It is best to let nature take its course, but rinsing sometimes will easily remove the residue. Leaching cures itself in a little time.
Surfactants: Necessary to a paint formula. They evaporate and never are a part of the dried paint. Slow drying due to coolness or humidity prevents the surfactants from evaporating and a blotchy sometimes glossy residue appears.