Marks showing through plaster/paint from plasterboard joints

cyclonebri1

In that case if it's on the joints then it's possible it's simply dry lined with taper edged board and then the joints filled rather than plaster skim the lot.
That means you have differing levels of absorption across the wall hence the marks.

As someone else said you thinned the first coat too much, way too much and are wrongly still thinning, another reason you can still see brush marks through the top coats.

:DStop being so dammed tight and put some paint on, you are taking money saving too far:rotfl::rotfl:

JustAnotherSaver

Just because i'm still posting here doesn't mean i've done nothing in between

They didn't use TE boards. I know this since i saw them. They were SE.

Yeah i may have thinned the first coat too much, but i've since gone with a 1:5 ratio as per the instructions on the tub for an additional two coats.

I have since hit that specific area god knows how many times since. 4, 5, 6 with that 1:5 ratio as per the tub instructions when i've finished off the other walls & have a bit left in the tub ... i'll stick it on there to see if it gets rid of it. It doesn't.


I'll just hang a picture there

victor2

Stain blocker or solvent based primer will most probably block whatever is showing through. Of course it will take a few coats of top paint to cover it, but it's worked where I've done it on persistent stains - and I only applied the primer over the stained area.

Or a picture will do the trick.

cyclonebri1

JustAnotherSaver wrote: »

Yeah i may have thinned the first coat too much, but i've since gone with a 1:5 ratio as per the instructions on the tub for an additional two coats.

I have since hit that specific area god knows how many times since. 4, 5, 6 with that 1:5 ratio as per the tub instructions when i've finished off the other walls & have a bit left in the tub ... i'll stick it on there to see if it gets rid of it. It doesn't.


I'll just hang a picture there

Look, give it a coat of straight water based gloss undercoat.

You seem to be getting problems that no one else gets, but few thin paint, if that don't work you need to nuke your house;);););)

Look, I've done this stuff for a lifetime, never have I thinned paint, the cheap stuff is too thin anyway.

The straight edged board could have been over preservative treated timber, god knows why, maybe preservative is seeping through?
I'm doubting this but simply use a non water based coat before you repaint

JustAnotherSaver

Just re-read what i posted.

Looks like i missed out a key piece of information.

The wall has been tanked & Sovereign Chemicals "strongly advise" not using any vapour barrier when painting.

I was in contact with Zinsser about one of their stain blockers & this was a vapour barrier.

That is why i created this post rather than just walking in to town & picking up a stain blocker, which is what the normal advice would be.

cyclonebri1

I'd still try treating just the affected area with water gloss undercoat.

Yes you will create a vapour barrier but only very locally, and moisture will simply wick out around the undercoated areas, your going to stop it breathing by applying a small band aid in effect.

I had missed the bit about not creating a VP but as above that is what I would still do.

JustAnotherSaver

Thanks.

I did speak with Sovereign & they seemed unsure about 'spot treating'. Their response made me think they weren't convinced by what they were saying & they were only sure about total coverage which i can understand.

Costly stuff for a little strip lol.

Still, i know you likely wont have the answer but i'd be interested in knowing why that small area has stained.
There's joins all over the walls & i'm sure they'll have used the same boards & method throughout ... so for this one area to stain? Strange.