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John Sez:
By John Harris, Belcaro Paint, Paint Chemist
We are just entering one of the two periods that happen each year that can cause special problems with exterior painting. In Colorado’s fall and spring seasons, because of the lower temperature and higher humidity, dew may form in the evenings on a freshly painted surfaces. Enough dew can form to cause water droplets to run down vertical surfaces. Moisture forming on a newly painted surface, before the paint has time to cure, brings ingredients normally within the new paint film to the surface. These ingredients are called surfactants (a fancy word for soaps). Their presence may cause streaks to appear on the new paint. The technical name for this phenomenon is Surfactant Leaching.
The down side of this occurrence is appearance only, as the integrity paint has not been harmed. Nature will eventually wash these streaks away.
Surfactant leaching is no one’s fault. Eventually all paint manufacturers and painters are faced with the probability of explaining this phenomena to their customers. Without a crystal ball or a perfect weather forecast, surfactant leaching is bound to happen. Sometimes it is possible to reduce the appearance of the streaks by gently washing the surface with a mild TSP solution a couple of days after the streaks have appeared. Doing a small test area first will give an idea of success potential in reducing the appearance of the streaks.
I hope the paint industry will eventually find a way to formulate paint so we no longer have to deal with this phenomena.
Please let me know if you have any questions about paint or painting.
Belcaro Paint & Decorating Center, Inc.
5475 Leetsdale Dr., Denver, CO 80246
303-757-5435
email us
Belcaro website
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