Poor Galvanised Metal

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.