Interior painting

[AndyDavis]

The walls and ceilings have been freshly plastered with Thistle Multi-finish. Before painting them is it a good idea put on some PVA to seal the surface? If so, how long does the PVA have to be left on before painting and how much do you need to dilute it.

 

[Thermo]

If its a normal room a mist coat of emulsion will seal it, dependent on the emulsion you use, the tub will give you the mix ratio. Leave the plaster as long as you can to dry out first. A mist coat gives a smoother finish than pva

Thermo

 

[AndyDavis]

Thanks, I was going to leave it for about four days before trying painting, is that enough or should I give it some more time?


By the way, whats the difference between a mist coat of emulsion and the commercial stuff like PVA and Dulux Plaster sealer.

 

[JohnBoyII]

See this link

http://www.diydoctor.org.uk/projects/paintnewplaster.htm

says to leave it for 4-6 weeks.

I read somewhere you shouldn't use PVA if you're going to use emulsion paint on the walls. Not sure why, maybe somebody knows.....

 

[Thermo]

emulsion paint in the main breathes, pva doesnt, therefore any trapped moisture is able to come out of the emulsioned walls

 

[AndyDavis]

Does that mean I might be better off using a "Trade" paint instead of the normal retail stuff because its thinner? So instead of two coats of the normal stuff maybe say three coats of the Trade paint.

 

[RKB]

I normally use a big tub of cheapo white emulsion from one of the sheds to seal newly skimmed plaster. This is normally sufficient to kill the suction of the new plaster. Once dry, two coats of the final colour and job done.
Hope that helps .....

 

[bobski]

you could use dwp trade emulsion which can go on within a day of drying out.

 

[mrscalex]

My walls have just been done with Thistle multi-finish. I left it around 4 days but the real test is to wait for the plaster to lighten and for a light film of salts to develop on the surface.

I used PVA (5:1) to seal and then painted with un-diluted vinyl silk. I know the vinyl silk was a mistake and now I'm wondering about the PVA due to the previous reply saying it won't let the plaster breath.

Put it this way. My paint did blister but bizarely it was where the skim coat was tightest, as tight as a thin skim of filler in fact. Fortunately for me it was where the kitchen units went but since this was only 2 weeks ago I will be worrying about the rest of it for sometime to come.

Last time I had walls skimmed I just used diluted Matt to seal with no problem and I wish I'd done the same thing this time.