Painting Plasterboard

No, just paint. with emulsion. Farrow and Ball has the biggest pigment loading by far.

You may need to use a lot of coats.. Biggest problem is that texture will vary slightly from area to area. Sometimes a light sand after the first coat helps this.

The first thing is to size it; that is put a layer of something cheap on to stop water absorbtion. I imagine you can stil buy size but pva will do. A thin (quick) coat of 10% solution in water, sprayed on with a garden spray will do.

The number of coats you need is largely dependent on how well you have taped the joints. All dark colours will highlight blemishes. White and creams not so much.

After a coat of contract matt, go over the boards again looking for irregularities. Use a fine filler and a broad scraper and work quickly then fine sandpaper it if needed.

But as it is in the spare room and you don't seem fussed, the demands on quality are less.

PVA is a poor base coat. Dilute emulsion is what to use.

I am not 100% certain, but I thought that emulsion paint effectively WAS PVA, loaded with pigment?

PVA is an emulsion, but I don't know if it's the one used in emulsion paint. It certainly doesn't behave in the same way, but that could be the effect of other components in the paint. Watered down PVA leaves a plastic surface behind which can be a complete disaster to try and paint over (either repells the wet paint, or it starts flaking off when you do the next coat), whereas watered down emulsion paint leaves a surface which is very easy to paint and it acts as a fine grade filler for small imperfections in the base surface.

If you get a film, you need more dilution. 10% pva is probably plenty for sealing plasterboard. Still, it's difficult to measure accurately, difficult to stir to a uniform consistency, and runs and drips everywhere. The own brand cheap emulsions are usually thin enough to use straight from the tin IME. Wallpaper paste is pretty good at reducing suction without leaving a residue

Thanks for all your help guys, think i'll go for watered down dulux.

Tom

And I think you are a f*ck head.

If you spray a thin layer of pva over the board, the stuff will be absorbed and leave a thin film to prevent further absorbtion.

PVA is a strange chemical. Mixed with meths it is a release agent for use in moulds. Mixed with almost anything it has the same effect of forming an impervious layer from which any further adhesion is prevented.

Howevewr if you do as I say -you silly sod, you will benefit from my experience.

However I don't suppose that you will take so much as an hint, as you have yet to catch on that the first person singular is -in English, a capital letter.

Be off with you, fool.

Sounds like a lousy paing then!

you make a surly drunk. your advice is not worth s*it.

there is a scientician on this NG that says that but hes wrong.

Its an emulsion formed by mixing poly vinyl alcohol-co-vinyl acetate (which is derived from poly vinyl acetate or PVA) and Poly methyl methacrylate (Acrylic).

Indeed. The reason to use watered down emulsion instead of watered down PVA is that if you c*ck up the dilution, the emulsion will be more forgiving, as it is already far more dilute. If you don't put enough water in PVA, you'll end up with a sticky mess.

However, for papered plasterboard, I wouldn't even bother with a watered down first coat. I reserve that for fresh plaster.

Christian.