sizing newly plastered walls

Hi

I was told with newly plastered walls to size them with a mixture of 50% emulsion 50% water before painting (to allow the plaster to absorb the moisture before putting emulsion on).

When I did this though the solution was so runny that I ended up with drips that showed through the paint and had to re-sand and do parts again.

If I'm using cheap emulsion to prep the walls do I really need to water it down or dosn't it matter?

Cheers

Duncan

Hi Duncan,

I think your talking about the mist coat. Sizing is what you do before papering (with a weak mix of paste) but the principle is the same.

Different paints, and indeed different surfaces, require a different mix. Some cheap paints are so thin that you may only need to add a bit of water. Others are a lot thicker and will require a lot more water. Also, the finish of your paster could make a difference. If it's like glass then its been over polished and ain't going to absorb anything so will need a light sand before painting.

Sounds to me like a combination of paint too thin, over application and possibly an over polished surface.

When you say drips, I assume you mean raised drips?

regards

Fred

Hi Fred

Thanks again for your advice! Yea I did mean raised drips, but what you've said makes perfect sense as I thought I'd just get the cheapest tub of emulsion and mix it up with water but common sense should have told me cheaper = thinner

The finish has never been like glass, the plaster seems to take the mix fairly well, I think what I'll do is experiement a bit next time using less water to get the mix right.

I've also noticed Dulux do a specific 'plaster sealer' for freshly plastered walls, would this be any good or a waste of money since I've got emulsion?

I'll remember it's called the 'mist' coat for future!

I've never used plaster sealer myself. I usually use Dulux Trade Supermatt. The tin says 1 part water 3 part paint but I usually mix it half and half without problem - the wall sucks it up.

Sounds like you've possibly applied too much paint which is what's caused the drips. When you experiment with the mix don't be over enthusiastic with loading the brush or roller. If it needs more you can stick more on - a lot easier than taking it off!

Regards

Fred

waste of money a decent emulsion paint mixed 1 water 4 paint will do just as good a job to seal the plaster a slight rub down first to get rid of snots then paint with the mix as above allow to dry then finish with topcoat job done