Recurring stain on newly painted ceiling

by Phil Cheers
(United Kingdom)

I applied a white emulsion (latex or water based paint) to a freshly plastered ceiling, which had been `sized` with no problems. There was a frieze spot between the ceiling and a picture rail that I cleaned and applied a white emulsion paint.

After the emulsion dried a brown stain started showing which looked as if the emulsion had reacted with something underneath it. I lightly sanded and washed the area prior to repainting it but the stain still appeared...??

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Oct 12, 2017

by: Shawn

Hi Phil,

You need to apply a solvent (oil, alkyd etc.) based stain blocker (not water based) prior to applying your emulsion (latex) paint.

The emulsion is water based and it is most likely reacting to something on the surface that is also water based. Changing to a coating, or primer sealer in this case, that has a different base will lock in the stain so that your emulsion will no longer discolour.

Your local paint store should be able to help with the type of blocker that you require.

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