POOR ALKALI RESISTANCE:
Colour loss and overall deterioration of paint film on fresh masonry.

POSSIBLE CAUSES:
• Solvent-based paint or water-based paint (vinyl acetate copolymers type) 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-resistance sealer or water-based primer, followed by a top quality pure acrylic exterior water-based paint. The acrylic binder in these paints resists alkali attack.

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