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Wednesday, November 10, 2010

What is Paint Leeching

I had a rare occurrence at a high profile job. We finished and the job looked spectacular. I did a normal final walk around and didn't find much of anything that my painters needed to touch up. A few days later (perhaps 4 or 5 days later) I got a call from the homeowner that there were stains all over his paint job. He had guessed that it was tannin from the cedar wood but the wood was old and I used a primer followed by two full top coats so I was skeptical that it could be tannin and after looking it over I was very doubtful because it was not in one confined area but all over the shake siding. After looking at it more closely and getting the Benjamin Moore Rep involved ( I used Benjamin Moore's Arbor Coat in a Neutral Base) we found out it was Surfactant Leeching.

Surfactant Leeching happens when the colorants in the paint take a long time to dry and end up raising to the surface of the coating and making a temporary stain mark. This cleans up with a cloth and some water ( and actually goes away on its own) but can cause a headache. It normally happens when the paint manufacturer uses a deep base (because a lot of colorant is added and thus takes longer to dry. The other circumstance that makes it happen is if you have a lot of rain shortly after the application or it is too cold. In this particular job we followed the manufactures recommendation regarding application temperature and technique (as we always do) however a day or so after we were done it rained harder than it had all year. I think that this rain (that went on for 2 days) caused the top coat to dry more slowly and thus produced the Leeching Colorants. We cleaned it up with some slightly damp cloths and the homeowner is sleeping easier. Of course we didn't charge for the extra cleaning. Even though the leeching would have gone away on its own, we'd rather have a happy customer with a perfect looking house then squabble over a few hours of cleaning.
Always apply products under manufacturers suggested temperatures and humidity and you should be fine. In the even you experience a rain storm 2 days after you finish and your paint starts looking funny. It is probably leeching and can be wiped off or will go away on its own.

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