A wall that leaves white dust on your hand has masonry paint that has reached the end of its binder life. Coating straight over it locks a weak layer underneath a fresh one, and the new paint fails at that hidden boundary rather than on the surface you can see.
UV breaks down the resin in masonry paint over years, leaving pigment behind with nothing binding it. South and west-facing elevations along the coast chalk faster than sheltered ones because of the extra sun and salt-laden wind they take.
A stabilising solution soaks into the loose surface and binds the powder back down before any coating goes on. On heavily chalked walls this sometimes needs two applications, and we test a small area first rather than assume one coat is enough.
A high-build or silicone-based masonry system keys well to a properly stabilised surface. Thin, cheaper masonry paints can still fail early on a wall that has chalked once already, since the underlying porosity has not gone away.
Rarely. Stabilising solution usually binds the loose surface without full removal, unless the paint is also flaking or blistering.
Rub a dark cloth firmly against the dry wall. Colour transferring onto the cloth means the paint has chalked and needs stabilising before recoating.
It can leave a slightly patchy sheen while wet, but this disappears once dry and does not affect the final topcoat colour.
Ask for a chalk test on your worst elevation before we quote the whole house.
Chalky masonry needs stabilising, not just a fresh coat, or the new paint fails where the old one already has.
Speak to a Hampshire commercial decorating contractor that turns up, communicates clearly and delivers a finish that lasts.
