Efflorescence is soluble salts within the masonry or mortar being carried to the surface by moisture as the wall dries, then left behind as a white, powdery deposit once the water evaporates. It looks alarming but is usually a drying-out process rather than a structural defect — the timing issue is what matters for paint.
New masonry and fresh render can take many months, sometimes over a year, to release all of their construction moisture. Painting before that process is complete traps salts and moisture behind the film, which then pushes through as blistering or flaking once the wall keeps trying to dry out.
We brush off loose deposits, take moisture readings across the wall and look at how the efflorescence is behaving over repeat visits — reducing over time is a good sign, persistent or worsening deposits suggest the wall needs longer.
A breathable masonry system that allows any remaining moisture vapour to pass through the film is the sensible choice on newer masonry, rather than a fully sealed coating that would simply relocate the same trapping problem to a later date.
No, that can dissolve the salts and drive them back into the wall, delaying the drying process. Dry brushing is the safer approach.
It varies with wall thickness, weather and render type, but new masonry commonly needs many months. We assess the individual wall rather than quote a fixed figure.
Not usually — it is more often a normal part of new material curing. Persistent efflorescence over a long period is worth investigating further, though.
Let us know roughly when the render or masonry was applied and we will advise on readiness to paint.
Efflorescence is usually the wall drying out — the fix is patience and the right breathable system, not an earlier coat of paint.
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