Mistake - put oil-based undercoat on plaster wall - help

[marge37]

I am a beginner and have bought the wrong undercoat today and didn't realise until I'd already covered most of a (small) wall.

So I've ended up applying an oil-based undercoat onto new plaster.

Does anyone know if this is going to damage the plaster?

And can I use a regular emulsion over the top?

I haven't used it on the other walls, so if I use an emulsion undercoat on those walls, will they look very different to the one that has the oil-based undercoat on?

Very frustrated that I've made such a silly mistake.

Thanks for any help you can give!

 

[joe-90]

You should be fine.

 

[sparkwright]

You must remember if any of your other walls are new bare plaster, you must firstly apply a 'mist' coat of diuted matt emulsion. This will prevent the emulsion peeling off, so it's very important.

You may notice the emulsion may appear a slightly different colour on top of the oil based undercoat you mentioned. This usually sorts itself out in a few days.

 

[TheDec]

I am a beginner and have bought the wrong undercoat today and didn't realise until I'd already covered most of a (small) wall.

So I've ended up applying an oil-based undercoat onto new plaster.

Does anyone know if this is going to damage the plaster?

And can I use a regular emulsion over the top?

I haven't used it on the other walls, so if I use an emulsion undercoat on those walls, will they look very different to the one that has the oil-based undercoat on?

Very frustrated that I've made such a silly mistake.



Thanks for any help you can give!

marge37,

Whilst I dont invisage any problems by applying an oil based u/c to plaster/skim, did you apply this system in an out of the tin direct manner or did you thin the system beforehand with either spirit or a turpentine substitute.

Dec

 

[ChrisR]

If the plaster was slightly damp and the undercoat thick, you might have a problem. Been there, got the peeled paint....
If the uc is thin enough it'll be slightly porous, but I have no idea how much it needs. Score with coarse paper?

 

[marge37]

Thanks for all your help on this.

I didn't thin the undercoat, no. But it went on dry plaster, and it dried OK.

Since posting, I've got the right paint and done the other walls. With the one I'd undercoated with oil-based paint, I sanded it before putting on emulsion. It's not perfect, but not too bad at all. With one more coat I reckon it'll be alright.

It's in a porch, so luckily not a wall I'm going to be looking at a lot!

I've looked again at the pot of paint I mistakenly bought. It's pretty misleading (for a novice at least) as it says it's multi-purpose. Only in the small type does is say it's oil-based.

Anyway, job almost complete and I'm much happier with it now. Thanks to people on this forum for some sanity. I've also had some help from a trade & retail paint place - so much more helpful than the likes of H'base.

This is a great site and I'll make sure I read up before getting started on the next project.

Thanks.