ceiling watermarks coming through paint

[moaner]

I have just brought my first house and am starting to redecorate. When we brought the house there were a few slight roof leaks which we have had fixed. These leaks have left brownish watermarks on the ceiling plaster. I have made a couple of coats of emulsion but the watermarks come straight through within a couple of minutes.
Is there a special product to seal the ceiling, or would a liberal coat of PVA suffice?
many thanks,
Dan

 

[D.S.D]

PVA works great................But not on ceilings or anything else that you want to put paint on. DO NOT USE PVA

You can use oilbase undercoat as a diy fix, just brush it on and when dry paint as normal. You could use zinsser123 which is a water based primer sealer or Zinsser Bin which is a shellac based primer sealer . You will find these at all good decorating outlets or you could try an aerosol stain block again by Zinser. the beauty of these is the drying times, very quick and both are something that me and most other pro deccys carry as normal.

 

[confidentincompetent]

Agre with you there dsd with the unders, and bin . But! have found the zinsser123 dont work on water stains.. I know it says it does somewhere in all that writing on tin ....

 

[D.S.D]

def does work mate but found that some stains have to be coated a few times sort of defeats the object really. Stuff the VOC's go with the solvent one every time

 

[JohnD]

Aluminium wood primer seals stains, because the particles of metal overlap and form a barrier as it dries.

 

[Zampa]

Aluminium wood primer seals stains, because the particles of metal overlap and form a barrier as it dries.

White knotting will also do the job...quick drying too.

 

[moaner]

Cheers everyone, I will look out for some of these products at the weekend...

 

[moaner]

Going back to D.S.D's first post it appears PVA is no good. This has got me thinking as I PVA'd some crumbly plaster in a bay window. What does the PVA do to the paint?....my dad recommended it......but thinking about it his idea of decorating is woodchip on all surfaces