Concentration of water-soluble ingredients on water-based paint, creating a blotchy, sometimes glossy appearance, often with a tan or brownish cast. More likely with tinted paints than with white or factory-coloured paints.

Possible cause

  • Painting in cool, humid conditions or just before they occur. The longer drying time allows the paint's water-soluble ingredients, which would normally evaporate, or be leached out by rain or dew, to rise to the surface before paint thoroughly dries
  • Contact of mist, dew or other moisture with the painted surface shortly after it has dried

 

Solution

Avoid painting in the late afternoon if cool, damp conditions are expected in the evening or overnight. If the problem occurs in the first day or so after the paint is applied, the water-soluble material can sometimes be rinsed off rather easily.

Fortunately, even more stubborn cases will generally weather off in a month or so. Surfactant leaching should not affect the ultimate durability of the coating. For more information, please consult our detailed Technical Advice note on the topic.


More problem solving advice

Yellowing

Development of a yellow cast in aging paint solvent-based enamels

Wrinkling

A rough, crinkled paint surface occurring when paint forms a 'skin'.

Tannin staining

Brownish or tan discoloration on the paint surface due to migration of tannins from the substrate through the paint film.