Bit of a technical question for any painter and decorator types out there.....

[CroissantNeuf]

The lower half of our bathroom walls are tongue and groove. Unfortunately when they were painted many years ago they weren't first treated with knotting compound so the stains where the knots are have come through the existing paint (a water-based eggshell).

Is there anything we can do before repainting that will stop the stain coming through again. I'm presuming that knotting compound cannot be used now as the wood is painted but is there anything else that we can use that will definitely work?

Thanks

i suspect you'll have to strip the paint off, paint on the knotting compound and repaint...

i could be talking out my arse tho.

No offence but I hope you're talking out of your arse too

(it will take a long, long time to strip it off and I don't fancy doing that)

don't blame you!

Thanks MrsM. I've just looked up the Polycell one on their website but I'm not sure whether it would work as it says "Permanently prevents existing stains reappearing through paint" which makes me think it might cover the stains that are there but if the knots in the wood continue to emit resin it won't stop that showing through.

Similarly it says "When stopping stains caused by water or damp, make sure that the original cause of the problem has been rectified" which could of course mean the resin again.

They've pretty much covered their backs in saying that it might not work.

If I can't find any other solution I might give it a go though.

How about painting over with Zinsser B.I.N. primer, and then your chosen colour of eggshell? Its a paint-over-anything primer. Some people use it for knotting anyway as it's shellac based. You can get it from decorator's merchants.

DH says zinsser bullseye should do the trick - although it might still come back through (he is a painter & decorator to trade

Fossil got there before me!

The local trade place steered me towards B.I.N. rather than bullseye as it's more knotproof, being shellac rather than water based. It was for bathroom panelling as well funnily enough.

we had this problem with our doors. i used zinnser BIN on the knots and repainted. over a year later and my doors are still stain free.

That sounds just the job - thank you all. I knew MN would have an answer.

I'll get DP to get some next time he's at Travis Perkins