Investigate and address the route of moisture before decoration.
All decorating problems
Moisture & stains · H&C advice
Efflorescence & white salt deposits
White crystalline deposits may appear on masonry or plaster.
- White powder or crystals on brickwork, render or walls.
- Deposits returning after they have been removed.
Understand before treating
What might cause it?
Similar-looking defects can have different causes. Assessment comes before product choice.
Moisture can carry soluble salts to the surface as it evaporates. Appearance alone does not establish why the wall is wet.
Preparation & next steps
How we approach it
Allow appropriate drying and remove deposits using a method suitable for the material.
Check salt recurrence and substrate condition before selecting a suitable breathable or other specified finish.
Painting over active salts or damp can lead to further failure. Avoid unverified chemical treatments and obtain advice on persistent deposits. Check current product technical data, safety instructions and compatibility; this guide is not a site diagnosis or a guaranteed repair specification.
The right system for the surface
Product selection matters
A suitable primer or sealer may be part of the preparation, but it cannot replace fixing the cause. Zinsser is one of the brands we use; the exact product depends on the surface, defect and intended finish.
Zinsser UK product guidanceOriginal H&C guidance. We are not approved, accredited or endorsed by Zinsser.
Local decorating help
Let’s look at the problem properly.
Share your postcode, the affected surface and what you’ve noticed. Preparation and repairs are assessed before a quote is agreed.