pva walls

[jay73]

hi all, im in a middle of a job and have a question,have anyone ever plastererd a wall without pva'in it first, the reason is when i was there the other day when i pva the wall it took ages to go off before i could plaster it, the walls have been painted. or is it a case of waiting .i no i should of pva'd it when i left the other day but had to go . ??? :-\

 

[Foxcroft]

PVA does 2 things, seals the wall, and creates a chemical key.

If the paint holds back the water well, then you could either give it a weak coat of PVA and leave it to dry, the another and skim when tacky. Or you could give it 1 good coat of 3-1 and skim when its tacky

 

[Basher]

while on about p.v.a i had a a strange thing happen today i the skim like started to sag down the wall how come this happened it has never happened to me before and whats the best way to get round it

 

[pwi]

no key or no suction what were you going on th basher

 

[carlos]

Had the same problem once before basher. I was going of a silk type paint. WBA next time.

 

[richardbrown]

you skimmed on the pva to early, it has to be nearly gone off on a surface like that because when you skim over the pva the moisture from the skim wets up the pva again so it slides

 

[kane]

Any-one has any idea the reason for this? Had a re-skim couple months ago the place had been stripped of wall-paper by a steamer and the areas which had no paint on and was the old grey finish-pva as usual went tacky prety quick so give it another coat of pva this surface calmed down a bit so then put first coat of finish when tacky.Now when i came back to put second coat on the finish was all splitting up (only on the un-painted old grey finish) after second coating it never had any probs! Just wanted to know if any-one has experienced this and why as i said never happened to me before or after this occation Cheers ???

 

[MFW]

Sounds like there was still high suction on the unpainted areas, despite your 2 coats of PVA.

 

[kane]

No MFW I done 3 coats of Pva on unpainted surfaces,But yea must have been still too high suction!

 

[Nisus]

If you put your 2nd coat of pva on & the 1st coat hadn't dried,
basically your just adding to the 1st coat & it's not sealing the surface
so it's still going to have high suction which is what would have caused
the splitting/crazing.
On high suction areas you need to leave your 1st coat to fully dry before applying 2nd coat
so that it seals the surface.