Seal plasterboard before plastering?

[Rob Nicholson]

Do you need to seal plasterboard before applying the finishing plaster?

Thanks, Rob.

[garryb59]

I'm not sure if the pros do, but whenever I've skimmed plasterboard I ALWAYS seal before hand. It just gives you so much more time to 'get the stuff up there' before you level off. You can get away with one coat, depending on what your joins are like, but I'll invariably give it too - applying the second one just as the first is setting.

With plastering I've always found two things are always worth observing:

1. Make sure the surface you're applying the finish too isn't too dry....wet it with water and/or pva.
2. Get it 'up there' as quick as you can. Don't mess around trying to smooth it out straight away, just concentrate on getting a coat on.
3. You're finish is only as good as the surface you're plastering. The more uneven the surface, the more coats you'll need.

God, it's knackering work. How those blokes do it day in day out.

Kind of satisfying though, when you start to get near those pros :-)

Garry

[Rob Nicholson]

I've been doing quite a bit of patching so far as I find a spray indespensible for damping the wall down.

I'm going to have a bash at the partition wall :-) It does take a certain knack doesn't it! I'm not sure I've got it either... But I agree with getting it on there as fast as possible. On the first attempt, I messed and meddled around trying to get it flat as I went along. Second patch and I go it on there, got it pretty level and then came back about 30 mins later and went over with a slightly sloppier mix and fill in the dips.

Of course, a small 2' square patch is a lot different to a 9' high wall :-)

Practise makes perfect I guess. Working with computers all day doesn't tone up the old upper arm muscles which seem useful when plastering.

That's what I'm thinking - I'll have a go. If it's crap, then I can still scrap it all off before it dries and get a pro in.

Cheers, Rob.

[Dave Jones]

No

[garryb59]

To do this, I'd pva 5:1 and let dry, then do another coat and when the second coat is just about dry [ie, sticky] the off you go. That will give you plenty of working time.

Don't forget to tape the joins too....very important. Wood moves. Scrim will facilitate the plaster not cracking at the joins where the boards meet.

It's all about picking up tips as you go along. I first saw a builder plaster a wall. After he'd applied the first coat, it looked like somebody trying to simulate the waves of an ocean. I remembering thinking, 'what a mess, surely can't leave it like that''. He went outside for a smoke, came back, wandered around for a while then began troweling out. Then he gave it another coat.

Walls and 'oles are mere trifles grasshopper....ceilings is where you is heading!

You can do it. Remembering of course, it also depends on what you're going to do afterwards. Are you looking to paint the wall, or apply wallpaper? But even if you're painting, there's always the 'lining paper' option.Don't forget there's always good old filler/artex/whatever to sort out any imperfections subsequently.

Something else to consider is tools and access to your mix. Get a flat board mounted on a table of similiar and pour your mixed plaster on the board and use a plasterers hawk to help move the plaster as quick as you can. You can easily bodge a hawk out of 4mm ply with a piece of thick dowel or rounded 2"x2" or something - again, makes the job easier. A hamk can carry several trowel fulls, meaning you're not going back and forth incessantly. And you can clean the trowel and hawk on the edge of the board every so often. Unfortunately you won't have the luxury of using a nice 14" trowel that's had 10 years of use with rounded edges and a razor blade edge! Plasterers get very attached to their trowels!

And get the surrounding area well sheeted, don't worry about the stuff flying everywhere, par for the course - certainly is with me.

And....use decent plaster too - and mix it well. Get plenty mixed for each coat. It's cheap enough. Thistle Mutifinish is about as good as it gets...IMO.

All just my 2p.

Good luck

Garry

[Andrew Gabriel]

I don't bother when using multifinish. However, make sure the mix is nice and sloppy -- should slide off the trowel when held vertical.

[John Rumm]

Thistle Multifinish onto dry plasterboard worked fine for me....

[Rob Nicholson]

Now sitting here sipping a pint of Black Sheep to celebrate my first big plaster job. And although I say so myself, it hasn't turned out bad at all :-)

Took best part of the afternoon though and completely knackered! I think you need a helper to mix the plaster for you... Certainly something more than hand mixing.

And I suppose the only tip I've got is "don't panic!". As somebody else said, just get it on the wall first and worry about levelling it out later. And don't worry if you carve out a groove - fill it, leave it slightly proud and return about 30 mins later and level it off.

Cheers, Rob.

[Andrew Gabriel]

I'm impressed if you handmixed a wall's worth of finish coat. I've done it with bonding coat, but it doesn't matter in that case if you don't get every last lump out. Also done it with sand/cement/lime in a wheelbarrow, and that's quite back breaking as it's very heavy, but it's easy to mix.

Strongly suggest you buy a plaster mixer for your drill next time. These work great (but watch you don't burn out the drill).

Yes. There's a limit to how smooth you can get the plaster at any one time, and repeatedly going over it makes it worse. You have to wait until it's gone off a bit more before you can smooth it any better.

[Rob Nicholson]

It wasn't a complete wall - fortunately. About 5' x 9' with 1' edge where I borrowed a bit of the bedroom in extending the bathroom so a full length bath fitted. Still, that was enough thank you :-)

Rob.