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Ask the Expert Question-and-Answer Archive

by Ron Joseph

June, 2009

Stained Cement

Q. Hi Ron, Two years ago we stained our outside patio with Behr concrete stain ... BIG mistake. Last summer re-rolled it because it was chipped and then sponged with translucent stain, to hide the chip marks. Now this summer the problem is much worse, more chips and peels, tough up is not working, any ideas would be welcomed other then tearing out the concrete, which is not an option. Thank You!

A. I have no idea why the concrete stain is chipping and peeling. Usually this is due to moisture coming up from the soil, through the concrete and pushing the stain off from the concrete. This could occur if you applied too thick a coat of stain. Do you know if a moisture barrier was placed under the concrete?

If there is no moisture barrier under the concrete, the more coats of stain you apply, the more difficult it will be for moisture in the concrete to escape. If moisture penetration is the root cause of the problem, then applying more stain will only worsen the problem of chipping and peeling .

There is a possibility that the failure is due to degradation of the stain by direct sunlight exposure. However, usually coatings made for exterior exposure are formulated with UV inhibitors that are intended to prevent degradation.

A third possibility is that the concrete was not properly cured before the stain was applied. In many cases, concrete that maintains too high a pH value (indicating that it is too alkaline) can cause paints to degrade.

Unless you can determine the root cause of the problem I suggest you do not keep applying more of the stain. In the worst case you might need to retain the services of a contractor who can abrasive blast clean the concrete to remove the stain altogether.


Ron Joseph

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