DIY Doctor

New Plaster - Followed Painting Advice but Need Help With Final Top Coat

Postby timtay » Tue Jul 15, 2014 5:58 pm

We had a plaster skim put over Artex, but stupidly painted vinyl emulsion onto it. We scraped and sanded all that off, which obviously took the top off the plaster. That was several months ago.

Yesterday, we wiped the plaster down with a mild sugar soap solution (it's in a kitchen, so had accumulated airborne grease etc).

Once that was dry, we put a mist coat of trade matt emulsion onto the plaster. This was like waterery milk, more than 50/50 easily.

It looked to be going well, and today was dry and seemed to have soaked in nicely.

However, we put a matt tester colour on top today, and once dry, to my horror, the tester coat could be scratched off with my (bitten) fingernail!

I then took a wet sponge to the misted area, and can virtually wipe off the mist coat back to the plaster, with some effort! It doesn't appear to have absorbed into the plaster, but it doesn't scrape or scratch off, it's only when wetted that is seems to come off. Much like, i guess, whitewash would on glass when wetted.

What have I done wrong, or is this normal? Do i need to mist again? Would a further coat be likely to be absorbed?

My guess with the tester colour, is that there was still absorbsion in the plaster, but because it was thicker paint, it sat on top much like vinyl does?

Was the mist coat too thin? I am worried that if i put a further mist coat on top, and it isn't absorbed, i am going to be in a right mess trying to get the matt off again like i did with the vinyl.

Could the plaster be damaged from all that went before?

What are my options for wallpapering, as this is seriously now fast becoming an option! Same process for sealing the plaster?

Or try a purpose made sealer on the wall instead of the trial and error i'm putting myself through?

Feeling desperate and in despair... and need some sound advice.
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Gorilla Glue heavy duty grab adhesive

Postby welsh brickie » Wed Jul 16, 2014 2:48 pm

paint a pva solution on the ceiling to seal the plaster, then paint
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Postby timtay » Wed Jul 16, 2014 2:55 pm

welsh brickie wrote:paint a pva solution on the ceiling to seal the plaster, then paint

eh?? Ceiling? Besides, from everything else i've read PVA is an absolute no-no.
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Postby theshedman » Thu Jul 17, 2014 7:20 am

Trade matt is not washable like a vinyl emulsion so will often wash off. A second mist coat may help to seal the new plaster then a couple of coats of a good vinyl emulsion should do it. If there is any grease or dirt on the ceiling or walls make sure it is all off before doing this. PVA shouldn't usually be used as a sealer but can if there is a problem with the surface you are preparing. The thing with PVA is that sometimes, but not always you may get bubbles in the finished surface. Another point is that you say you painted it and then when you thought it had dried you managed to scrape a bit off. Well it may be that although it was touch dry it probably wasn't dry dry as this often takes at least 24 hours so that it has a chance to harden.
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