A plasterer told me he once started work on a ceiling and it went off straight away. It turned out the plasterboard had been up too long and had dried out.
I am just about to skim a couple of small areas, the biggest is 4 square meteres and the board is bone-dry without any smell. It has been up for a year.
Shall I just go for it, or in your experience, would you wet if first? If so how?
Cheers Robin Pain
snipped-for-privacy@tesco.net wrote to uk.d-i-y:
Wet it, but not to much that it is soaking, with a basin of water and a big paint brush. Remember to shake the excess water off the brush before you swing it above your head.
An alternative to the plastere's big bristle brush waved at the wall is a pump up garden sprayer - the kind you use for weedkiller.
Filled with clean water this can give a fine misty spray and be used to wet down large areas quite quickly.
For a small area a hand sprayer (just a bottle with a trigger top) would no doubt do the same.
HTH Dave R
Strange, I thought that was why it was called "dry-wall". Old plaster on the other hand goes off quickly.
Alan
...and when new plaster touches old plaster, at least that's what the literature says so I have always kept everything spotless and thought it mattered until:-
The chap who skimmed the ceiling turned up and had a good laugh at my plaster's wheel. He produced a 450 watt electric drill with a paint mixer. The mixer was covered in old plaster. He mixed it in a large plastic paint container, about two feet tall and about 9 inches across that also had old plaster stuck around the bottom.
He mixed up a huge amount so that the thing was nearly full and I could hardly lift it. By the time I had mixed up half as much again and staggered in with it, he had most of the first mix up.
So this "remove all traces of old plaster" is a myth? (If mix large amounts and you're quick).
Robin
Thanks Big Wallop, that was hint I wanted to hear, (I found out about the water on the head thing already)
Robin
I think the hand sprayer is a great idea, it's only a small area.
[I built my extension with the usual cheap Celcon building blocks but I could never get them wet enough, long enough, with the bucket of water/paint brush method (in the summer heat). It was more exhausting leaping up and down painting it with water than applying the render so in the end I just blasted the wall with a hose pipe.The original part of the house (1955) used a denser block, whitish, with a cavity, this only needed a single touch with a wet brush and you *had* to wait for fifteen minutes or more before you were *able* float it.]
Robin
I don't follow this at all - my immediate reaction was "the plaster's having a laugh, surely...". But enough folk have responded to make me think it must be true. Could somebody explain?!
Firstly, plasterboard is encased in paper, so the finishing plaster has no direct contact with the plaster component of plasterboard. Secondly, plasterers are commonly required to apply a skim coat over an old, knackered plastered ceiling to provide a decent finish prior to redecorating; and you don't get plaster much older than that! So I'm puzzled.
David
Plaster board is porous. That's why building regs specify foil-backed boards for ceilings (as a vapour barrier).
Tradesmen are quick, you may not notice the little touches they do like e.g. damping down, and *that* is the trick.
I am just a fair-weather amateur so everything I do is in the summer. The mistake I consistently make is too dry e.g. I have to constantly remind myself "make it wetter than you think" (the bricks, etc, not the mix).
If you inadvertantly saturate some bricks, no probs they will be useable in half an hour (brick-laying-wise), but when a barrow-load of render falls off a too-dry-wall it is most annoying and hard work reviving it by hand not to mention a time-waste.
Robin
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.