Newly plastered walls

I've had the walls in my living rooms replastered and now they need painting. I am wondering if I should coat them with some sort of primer before painting, or is it best to just give two coats of paint ?

 

Advice generally seems to be to 'mist coat' first. That is using diluted emulsion. My brother-in-law is a builder and never does that, just applies 2 normal coats. Results when he did our conservatory look good to me. A diluted first coat would reduce the cost a little.

 

I think some paint manufacturers recommend a first coat of slightly diluted paint ( ten parts paint to one of water) or you can buy special primer paint for newly plastered walls, which does the same thing.

 

Thank you both

 

I believe the old advice was to let the new plaster dry out thoroughly before painting, weeks or months? but don't know whether this advice is still adhered to?

 

I seem to remember you can apply a watery coat of PVA as a sealer before painting but I'm not sure if that is still considered a good idea.

 

Thanks @lizzie27, the walls were plastered last November so it's been almost a year

Thanks for your reply @pete that's what I was hoping to clarify. I think the first two comments have enlightened me about it

 

Don't use a PVA coat, just use a diluted mist coat is the standard specification from paint manufacturers.

 

We were always advised to use diluted PVA. It worked well, but diluted paint would be the go to now I think. I did that for the extension here. Two coats of paint in the standard way would also be fine, but diluted would obviously be cheaper, so it depends on your budget etc.
I tend to do two coats of paint anyway to get a good result, and sometimes the 2nd coat doesn't need to be quite so thorough, but it would also depend on the colour. Darker ones need more attention than paler ones.

 

When we had our ceiling plastered a couple of years ago, we were told to let it dry out completely. Then use the diluted first coat ( messy!) as the plaster would tend to suck in the moisture. Advice was that if applying an undiluted first coat, the plaster could suck out some of that moisture, and the paint might peel. We did need to apply quite a few coats in the end to get the ceiling to the whiteness I wanted. We also found a difference in the ‘matt’ness of different brands of paint! Usually very pleased with our usual DIY store own brand, but somehow it didn’t look right, so we had to redo it with a branded version, that was a bit of a surprise. I think it was the way the light reflected off the ceiling, but there was a definite difference between the two supposedly matt products.

 

The reason a diluted (aka mist) coat is applied is it is absorbed into the plaster a little more and enables subsequent coats to bond correctly, failure to do so often means the first coat just sits on the surface and can peel off - I have seen it loads of times where you can get a scraper under a peeling edge and it all just lifts off, a mist coat helps to prevent that.

A PVA coat is usually frowned on as it fully seals the plaster and the paint won't get in to the plaster at all, not too much of a problem in itself as the paint will adhere to the PVA ok but the PVA sealer coat will dry shiny and the emulsion won't be absorbed in to it and it will just slide around on top of it during application and won't cover as well, takes ages to dry too. Just use a mist coat, it's overall better and no need to buy PVA.

 

Perhaps there's also a difference if it's a plastered wall as opposed to plasterboard.
The builder who did work for me at a previous house gave me a large container of PVA, which I still have, and use. I didn't have any problem with the emulsion not adhering well to it.
Some of the walls in that property were plastered and some were plasterboard. Old, Victorian property, so a mix of finishes in various parts. The main alteration was a kitchen that was opened up, and incorporated other small rooms, but there were other areas too. Different paints, and no problem.

 

I think the pva should be diluted to a point where it doesn't dry shiny.

But I can see the benefits of just using a diluted first coat of paint which is probably what I would do these days.

Thinking back through my foggy recollections it may have been recommended to use pva if you were going to apply wallpaper.

 

When I used to paper walls I'd coat them with the wallpaper paste before hanging the sheet of paper. I just paint the walls now