Causes:
All latex paints contain detergent-like materials called
surfactants that are necessary for the stability of the
paint formulation. In cases where surfactant is leaching
from the dried film, this material will dissipate in small
amounts. Surfactants tend to come out of the film slowly,
and are easily removed by normal weathering. Under certain
curing conditions, such as low temperatures, condensing
moisture, etc., this leaching process occurs rapidly and
results in a surfactant build-up on the surface. Leached
surfactant can appear as a thick brown syrup-like deposit
or rundown. On occasion, it may assume a white crystalline
form. Surfactant leaching is not limited to exterior
coatings. It may appear in bathrooms or other areas where
moisture condenses on walls. In these instances, a clear
amber glossy rundown will be visible.
Solution:
Surfactants can be removed with a fine mist from a garden
hose or by rubbing with a wet cloth.
Often the best solution is to do nothing and let nature
take its course. The surfactant will do no harm and time
will correct the problem.
Surfactants must be removed prior to painting. |
