Exterior Poor Alkali Resistance

Poor Alkali Resistance: Color loss and overall deterioration of paint film on fresh masonry.

Possible Cause:

Oil-based paint or vinyl acrylic latex paint was applied to new masonry that has not cured for a full year. Fresh masonry is likely to contain lime, which is very alkaline. Until the lime has a chance to react with carbon dioxide from the air, the alkalinity of the masonry remains so high that it can attack the integrity of the paint film.

Solution:

Allow masonry surfaces to cure for at least 30 days, and ideally for a full year, before painting. If this is not possible, the painter should apply a quality, alkali-resistant sealer or latex primer, followed by a top quality 100 percent acrylic latex exterior paint. The acrylic binder in these paints resists alkali attack.