HELP - stain coming through oil based paint

[66skeghandyman]

Hi everyone hope you can help - i am doing some decorating for a friend and this is the problem i am having - I have stripped the wallpaper as it looked as though patches of damp were causing the paper to peel away and discolour, i tested the walls with a damp meter and they were within acceptable limits to be on the safe side i thought i would use oil based gloss undercoat (leyland trade) I applied undercoat and within minutes yellow staining has shown through!

I then got some stain sealer (crown i think) this is way thicker and applied - once again it stained within minutes.

The stains are blotchy

The room is upstairs with two exterior walls - the house was built 1820s and has had the brickwork outside painted

Any help would be appreciated

Thanks

 

[footprints]

Hi 66skeghandyman,

You say the damp level was acceptable, was it bone dry? Painting an oil based paint over any damp at all will be a problem. Has the source of damp been rectified, was that why the outside was painted?

Sometimes stain blockers like Zinsser (my preferred choice) will let the stain through the first coat but will then “lock” it in so when dry the next coat will not show the stain. It would be worth trying a second coat of the stain blocker to see if it works.

Good luck.

 

[elrobbo82]

have you tried a shellac based stain block? zinsser BIN is very good and the stain should not bleed through. you still need to find the caurse of the damp though and rectify first.

 

[TheDec]

The reason for your problem points directly to damp, you first have to ascertain the cause of this and then provide a cure, then allow the walls to fully dry before sealing the stained areas with an Alkali Resistant Primer.

Dec