New plaster - diluted 1st coat of paint.

Dulux would say that - you use more of their paint! I always seal new plaster walls, always, either with a 5:1 PVA or a highly diluted emulsion mix. I'd say 50:50 is minimum, but it largely depnds on the state of your emulsion before you start, some are thinner than others. It can get a bit messy, depending on how diluted you go, but it's well worth the effort. I aim for a thick milky/single cream type texture. Dust sheets are your friends.

Garry

Probably not. In fact using Supermatt without water still achieves a good result.

Actually, 1:5 makes a big difference to the paint, and even 1:10 is quite noticable. With 1:1 you would end up with most of the paint on the floor without it ever getting as far as the wall;-)

Agreed. But that's the difference between ya average DIYer and ya real pro tosher :-)

Garry

I used the recommended 1:4 with Dulux Trade Supermatt and it came up lovely. Subsequent undiluted coats went on fine, without excessive suction or cracking.

Christian.

Not necessarily. New plaster can suck the water out of paint very quickly. I used 50:50 mix on some walls and ceilings and it still dried out too quick.

YMMV Mark