Painting over stain

Hi all,
I have a brown stain (no jokes please) in the corner of my ceiling that won't cover up no matter how many coats of emulsion I give it.
The ceiling is of lathe and plaster construction and is painted in Dulux white emulsion. I think the original stain was caused by a leak from the bath waste a couple of years ago that has long since been cured and fully dried out.
Is there a product on the market that I can use to seal the ceiling to stop this stain coming back?
Thanks for any advice, Sean
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try painting a light coloured oil based paint such as undercoat over the stain, allow to dry then paint over normally with emulsion. If that doesnt work you can always use an aluminium sealer/primer but you may need 5-6 coats of emulsion over the aluminium to cover that. The aluminium sealer is used after a fire where oily smoke has got into the plaster. It seals everything but needs a bit of drying time plus several coats to cover especially a light coloured emuldion. The silver seems to show through even when covered with 2-3 coats emulsion
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Sean Delere wrote:

I've used (sucessfully) Polycell Stain Stop - http://www.diy.com/bq/product/product.jhtml?PRODID 834&CATID•115
I've also used, with less success, white oil based undercoat.
I've got a similar problem to yours in one of our bedrooms which will be painted over Christmas. I'm going to try Screwfix's Stain Block - item code 15679. Anyone tried this?
Andy
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fully
stop
Sean,
I've always found that stains can be stopped coming through emulsion using any old bit of gloss (or even varnish) that you have left over. Brush on a generous coat and when dry overpaint with the emulsion - save your money and don't buy a specialist product (unless the stain is something very odd!)
Andrew Mawson
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I used a stain sealing paint (forget the name) for a nicotine stained ceiling and it was overpriced and useless. Then I went back to using a solvent based undercoat and it worked perfectly.
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Thanks for all the tips.
As I have a tin of white gloss I will try that first before moving on to the Polycell sealer.
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sean snipped-for-privacy@hotmail.com says...

Did anybody mention varnish? We had grease stains on a ceiling from something weird somebody had done to the roof or in the loft, and a local builder suggested painting over them with varnish before emulsioning. Worked like a charm.
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says...

the
Yep !
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So far so good.
I painted the area with gloss, let it dry for an hour or so then went over with emulsion.
This was yesterday and the stain is yet to show its face.
Sean
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On Sat, 13 Dec 2003 09:40:49 +0000 (UTC), "Sean Delere"

Interesting. I've always believed that painting on top of gloss was a no-no, unless you prepared the surface first by rubbing to provide a key for other paint to cling to.
Maybe my information is out of date though.
PoP
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I had a similar believe which is why I emulsioned over the gloss before it had fully hardened.
I am not sure if this was the correct thing to do but it does seem to have worked.
Sean
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