got a recurrent stain in my ceiling help!

[zena]

I am painting a ceiling which was previously painted by the previous owner and subsequently papered which I have taken the paper off to reveal the painted farely smooth if not perfect plasted ceiling which has a couple of layers of what looks like emultion on it. I am trying to paint the ceiling with white dulux ceiling paint (silk) and after the first coat the stain af a previous dried out stain yellowish colour keeps coming back through. I am thinking this is the stain from 8 years ago when the roof I am told ahd a leak but doe not leak now. why might this stain be coming through and what can I use to stop it appearing through the paintwork?

Pleas help!

 

[noseall]

sometimes it can help to apply gloss paint to the stain, then emulsion over,but i bet nestor.k. has a better idea!

 

[JohnD]

Ceiling stain after a leak.

Process:

mend the leak, and check it is gone, and the ceiling is dry (check from the roof side as well)

If any black mildew, apply bleach solution (with a sponge) or mildew spray to kill it, then wash it off.

Let it dry out

Apply two coats of "stain block" sealant (like a white paint) or, of aluminium wood primer (looks like silver paint, has tiny flakes of aluminium in it)

Put on your ceiling paint.

The problem you have got might be that you are using a water based emulsion paint, which is dissolving the dirt stain so that it soaks into the new paint before it dries. The stain blocker or aluminium primer forms an impermeable layer so it cant.

There is an alternative possibility:

After fixing the original leak, and checking it, I once got another leak above the same room, which was a very confusing problem.

 

[Nestor_Kelebay]

Zena:

I agree with John that you need to be sure that original leak is fixed.

Perhaps cover that part of the ceiling with clear plastic ( like a plastic bag split open or wax paper or Saran Wrap) and tape the perimeter of the plastic to the ceiling. If any condensation forms on the ceiling side of the plastic within a few days, then that's due to moisture evaporating from the damp plaster, and it means the leak is still a problem.

As for killing stains that bleed through paints, go read my response in this thread in the Painting & Decorating forum, and it'll answer this "stain bleeding through paint" question and all such questions for the rest of your life:

"what primer to use on stained wood?" posted by Gille on Monday, January 9th.