Poor alkali resistance is the loss of colour and overall deterioration of paint film on fresh masonry.

Poor alkali resistance

Possible Cause

Poor alkali resistance is the loss of colour and overall deterioration of paint film on fresh masonry.

It occurs when oil-based paint is applied to new masonry that has not fully cured (at least one year). Fresh masonry contains lime and cement, which are 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 compromise of the paint film performance.

 

Solution

Always allow fresh masonry surfaces to cure for a minimum of 30 days, ideally for a full year, before painting. If this is not possible, apply a quality, alkali-resistant sealer or water-based primer. Using Dulux 1 Step Acrylic Primer, Sealer and Undercoat followed by Dulux Weathershield is recommended.


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