Paint blistering.


Postby hibeejo » Sun Mar 02, 2008 8:57 pm

I recently had all our walls skimmed in our flat. The plasterer advised to leave for 4-5 days before doing anything with the wall. About 8 days afterwards i coated the walls with watered down PVA glue. after a day or so I gave it its first coat of matt emulsion, then once dried gave it a second coat. I then left it for about 2 weeks. When I applied the 1st coat of the colour, one area of a wall has started to bubble when the roller applies pressure to it.

I now realise that this is because that section of the wall never dried properly. I have stripped most of the area down to the new plaster. what is the best way to acheive a seamless finish? would I have to strip that whole wall?

please advise , im stuck
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Postby chris_on_tour2002 » Tue Mar 11, 2008 12:07 am

buy a ready mixed plaster scrim and a taping knife. you can achiece a very thin, fine fill with this stuff and it sands to a smooth finish (fine-ish sandpaper, say 180 grit)
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Postby rosebery » Tue Mar 11, 2008 12:21 am

[quote="hibeejo"]I now realise that this is because that section of the wall never dried properly."

No its because when you put the wet paint on the PVA it became live again and roller lifted the paint and PVA off the plaster because it wasn't sticking to it any more.

As a matter of interest what emulsion did you use?

Where this idea comes from of PVAing new plaster before painting totally escapes me - always leads to disaster.

If you've stripped most of the PVA off I'd say - yes finish it.

To be absolutely certain there no PVA left I'd go over it with Zinsser BIN as a priming coat or if the cost of the stuff puts you off then a spirit based undercoat will do just as well.

If you are happy that the PVA is all off go over it with a mist coat of 50/50 water to paint if using something like Dulux Supermatt or Trade Vinyl Matt or less water for thinner emulsions. Don't use Dulux Rich Matt - that won't stick to,new plaster and don't use silk finish either.

Then you can reapply your main paint coats.

Hope this helps and sorry you've got all this extra work.

Cheers
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Postby the paint pot » Tue Mar 18, 2008 11:49 pm

I HAVE BEEN A DECORATER FOR 10 YEAR AND YOU MUST USE A 4 TO 1 (4 PARTS PAINT 1 PART WATER) ON NEW PLASTER AND I WOULD NOT RECOMMEND USING PVA AS THE PLASTER WILL NOT SOAK UP THE PIGMENT
HOPE THIS HELPS
THE PAINT POT
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Postby mraich » Mon May 05, 2008 11:01 pm

[quote="the paint pot"]I HAVE BEEN A DECORATER FOR 10 YEAR AND YOU MUST USE A 4 TO 1 (4 PARTS PAINT 1 PART WATER) ON NEW PLASTER AND I WOULD NOT RECOMMEND USING PVA AS THE PLASTER WILL NOT SOAK UP THE PIGMENT
HOPE THIS HELPS
THE PAINT POT[/quote] Slightly different problem. I have just painted the walls in my hallway with a matt emulsion. Wife doesn't like the colour. Can a sheen paint be painted over the emulsion?
Thanks.
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Postby rosebery » Tue May 06, 2008 9:37 am

Matt, Silk and Soft Sheen are all emulsions.

The problems occur when applying matt over silk or soft sheen 'cos the matt doesn't take. The other way will be OK just give it a light sanding frst though.

BTW this question really required a new thread rather than resurrecting one over 2 months old. It's easier for you and also for those reading and answering. No offence meant.

Cheers
rosebery
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Postby al fresco » Tue May 13, 2008 4:40 pm

We had an extension built some months ago now and have just got around to decorating so the plasterboard and skimming should have been well dried.

The problem has arisen not so much on the new wall but a couple of feet along the original wall where the plaint and skimming has lifted. I had applied a mix (1 part water to 5 emulsion) to seal as recommended by my builder which caused on problems at all on the new wall (or indeed on the opposite inner wall) but on applying the first coat of emulsion proper has now lifted down the wall (from top to bottom) where the new skimming has been phased in.

I've been recommended to use Polyfilla to replace the plaster skim where it's lifted and seal it with PVA. I notice that some of you strongly disaprove of the PVA so I propose to try again with the emulsion mix before painting.

I'm wondering what's the best way to begin. Dry sandpaper or use a fine wet pad. The affected area is probably ony a couple of inches across.

Some confidence building advice would be most welcome. :?

PS: Problems appears to be where the plasterer has skimmed over the old emulsion.
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Postby mraich » Thu May 15, 2008 12:44 am

[quote="rosebery"]Matt, Silk and Soft Sheen are all emulsions.

The problems occur when applying matt over silk or soft sheen 'cos the matt doesn't take. The other way will be OK just give it a light sanding frst though.

BTW this question really required a new thread rather than resurrecting one over 2 months old. It's easier for you and also for those reading and answering. No offence meant.

Cheers[/quote] Thank you Roseberry. Apologies for the delay. I take your point on 'New thread'. Just hadn't got the hang of this topic business. Think I have it now.
mraich
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