After painting an aluminum siding with a latex house paint, there where sections of the house that contained streaks. What happened?

When dew forms on latex paints before the film has fully cured, a concentrated residue from the paint material can form on the surface, causing staining, unsightly runs and gloss patterns. This finish problem is known as surfactant leaching. Aluminum siding is particularly prone to surfactant leaching because this type of substrate reacts to temperature changes faster than wood. To avoid this problem, apply paint during temperatures that allow proper curing. Avoid painting during hot and humid days with significantly cooler evening temperatures. ... more