Stains on plaster walls still

Following a chimney leakage am having problems getting rid of patchy stains on wall, have stripped the wall-paper and applied thinned down primer, along with some "stuff" from a squeezy tube before applying matching emulsion which is on adjoining paper. The stains are fainter but still there. Do I need to apply a lining paper and, if so, what sort. Am not used to papering and would prefer not to !

 

Can you define:

You need to either use a stain blocking paint/spray or a coat of thinned oil based undercoat to stop water stains leaching through water based emulsions

 

"Stuff" was a sqeezy tube with a sponge at the end, I think it was made by Polycell ? I did try a coat of thinned down oil based paint as recommended by a previous poster too, but to no avail I'm afraid. I have now applied about 4 - 5 coats of emulsion over the stains with minor success. As this is a chimney breast I wonder if the stains are in the brickwork, the walls are 102 years old and I wonder if the roof leak brought them out or they could have been there under the emulsioned wall-paper for some time without showing. The wall-paper was just removed from this part of the wall as it had lost adhesion after the leak (now cured)

 

You could put 100 coats of emulsion over, and the stain would still bleed through.

Another oil-based product is worth a try, a stain block or similar.

 

Emulsion is water based so will activate the stain each time. An oil based or maybe even a shellac based sealer will stop it. If your using oil based undercoat don't thin it too much or it will fail to seal the area.

 

Thanks, will coat again, do I need to remove the emulsion before-hand.

 

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