Poor alkali resistance can cause color loss and overall deterioration of paint film on fresh masonry.
What Causes It?
Applying oil-based paint or vinyl acrylic latex paint to new masonry that has not cured for a full year may lead to poor alkali resistance.
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 that it can attack the integrity of the
How to Solve It
Allow masonry surfaces to cure for at least 30 days, and ideally for a full year, before painting. If this is not possible, you should apply a quality, alkali-resistant sealer, or latex primer, followed by a top-quality 100% acrylic latex exterior paint.
The acrylic binder in these paints resists alkali attack.
Note: Images provided by The Rohm & Hass Paint Quality Institute.