Problem Solver - Efflorescence
Efflorescence is a crystaline deposit on surfaces of masonry, stucco or concrete. It is whitish in appearance, caused by water migration being driven out as a result of the heat of hydration bring salts to the surface.
Stage 1 - Preparation
Dry brush the surface down using a stiff bristle brush to remove any loose materials
If any mould or mildew is apparent, treat with a suitable fungicidal solution, rinse again with clean water and allow to dry.
If painted, check for cracks or areas of blown render where water could penetrate such as behind downpipes and gutters and make good.
Stage 2 - Basecoat
Once the surface is clean and all loose material has been removed, treat with an Alkali Resisting Primer or suitable plaster primer and allow to dry.
Stage 3 - Topcoat
Apply a suitable topcoat