Painting New Plaster

nelly_2

home_alone wrote: »

The best of both worlds is use a cheap emulsion watered down with PVA, from the horses mouth.
PVA from the horses mouth?

Well b*gger me I allways did wonder where it came from

andipandi_2

nelly wrote: »

home_alone wrote: »

The best of both worlds is use a cheap emulsion watered down with PVA, from the horses mouth.
PVA from the horses mouth?

Well b*gger me I allways did wonder where it came from

:rotfl: :rotfl: :rotfl: :rotfl: :rotfl:

Debt_Free_Chick

home_alone wrote: »

Plasterers use PVA because it seals (although not completely waterproof) and delays water absorption therefore allowing more time, therefore larger surfaces can be plastered (jobs undertaken previously by 2 or more plasterers.

But, surely, the PVA seals moisture IN to the plaster so that it can't escape and is therefore trapped. So as it's not completely waterproof, the trapped moisture will eventually escape and cause bubbling to the painted surface?

home_alone

Debt_Free_Chick wrote: »

But, surely, the PVA seals moisture IN to the plaster so that it can't escape and is therefore trapped. So as it's not completely waterproof, the trapped moisture will eventually escape and cause bubbling to the painted surface?

You wait for the plaster to dry first no point in doing anything untill then, the discussion on this point was about the use of PVA before plastering to stop the plaster from drying out to quickly when applied (my second para).

handyman.

yes home alone, thats what you correctly said...........this is where the confusion starts with pva.

Pva for plastering
No pva for painting.......as per BS6150 (or so I'm told )

nickj_2

i painted a landing and stairs last year , there were a few hairline cracks that were filled , after 3 months the customer called me back , in a couple of places the paint had cracked to the plaster , i got a stripping knife a peeled all layers of paint of back to the plaster , after consulting with the customer it appears that they stripped all the paint off years ago and pva'd the walls and then painted them . when i painted them this has a soaking / lifting effect on the first coat of paint .leaving the paint hovering on the surface rather than gripping it , as i pointed out , it was not my paint that had caused it to lift .
use pva on bare plaster at your own risk ...................... don't come crying on here when it goes pete tong

home_alone

handyman. wrote: »

yes home alone, thats what you correctly said...........this is where the confusion starts with pva.

Pva for plastering
No pva for painting.......as per BS6150 (or so I'm told )

I raise your BS6150 and play BS5262, BS5492, BS5270 (so ive been told)

This is my final word promise, I have had no problems with the use of PVA prior to painting after many years of practice there are some on here that have, some have not, I know that the quaility gap between various brands of PVA is huge (there are brands we have used and will use no more because even plaster failed to adhere, that cost money) I wish all of you much success with whatever method you use.
PS I wish I could blame all the cracks in plaster to PVA instead of lousy plaster boarding.
gary

zolablue25

Wish I'd read this thread a couple of weeks ago. I primed our new plasterwork with diluted PVA and am now about to paint. I guess my options are: Sand down the surface to remove the PVA or Paint and hope for the best? (and hope home_alone is right!)

home_alone

zolablue25 wrote: »

Wish I'd read this thread a couple of weeks ago. I primed our new plasterwork with diluted PVA and am now about to paint. I guess my options are: Sand down the surface to remove the PVA or Paint and hope for the best? (and hope home_alone is right!)

Just paint over the PVA it will depend on the quality of the PVA but I imagine that half of the people that have new extensions etc and do the paintting themselves use a diluted PVA as a base. The ulitmate test is to PVA one wall (newly plastered) and watered down emulsion a 2nd wall leave for a reasonable time then paint finish then leave for while then paper both walls then after a year remove the paper my bet is the PVAd wall will retain its paint and the emulsioned wall will shed most of its paint with the paper, it happened to me many years ago, but trial and error and hindsight are wonderful things in a DIY experts handbook. All comments on websites such as this one are opinions only we are all entitled to have them.

gary

nickj_2

it will probably be alright until you redecorate , the moisture from new emulsion will cause the old paint to lift from the pva