Naff one coat plaster

[Broadback]

Is it my lack of skill or the plaster? I have had to cut out a smallish area of plaster to fill in a large crack. Normally I use undercoat and the finish plaster, though no expert I can usually get a reasonable finish. However the sheds only seem to do large bags of undercoat and finishing plaster, which would be a waste, so I purchased one coat plaster, however the finish looks more like rough cast than plaster. What am I doing wrong, or is one coat plaster normally difficult to finish satisfactorily?

[Scott M]

I used a load once when first playing with plaster and it was very course and not at all finishable in a good way. Having played with finishing plaster since, I'd be tempted to use that exclusively for filling chases, etc.

Scott

[Tim Lamb]

In message , Broadback writes

Pretty much my experience:-(

Partly lack of skill but floats used once in 10 years a main contributor. For my next attempt, I will leave space for a finish coat of polyfilla or some such.

[polygonum]

Last time I had a big bit to do, got some board fixing plaster. Nice and smooth, slower going off. Relatively sensibly sized bags.

[Jim K]

some what?

Jim K

[polygonum]

[Robin]

FWIW you are not alone. I've failed miserably with that stuff - even when I've applied it in two coats as recommended in the past here.

[Jim K]

that's also in a 25kg bag and almost twice as expensive than finish plaster?

and you used this to do a "big bit" of what?

way to go - er not

Jim K

[Jim K]

also setting time is IIRC 45 mins - i.e. same as more usual plasters...

did you mean something else?

Jim K

[polygonum]

No - but I did only give that link as the first one for that sort of product. The question had been "some what?" - rather than "where from and at what price?"

may be other manufacturers, package sizes, retailers and prices. This is one example only.

Setting time to me seems slower - certainly had no problems with it in that regard wheres I often do with other products.

[Jim K]

squirm, squirm

squirm, squirm

"may be"? which did you use then? in the small bags remember? oh let me guess:- it was decades ago - before the widespread introduction of plasterboards and dry lining in fact...........

maybe start reading the use & application notes usually printed on the various different product bags?

Jim K

[newshound]

What I use isn't an adhesive, it is the filler for taper edge boards. Apparently expensive, but it does not go off like finish plaster. My bag must be 10 years old and it was still working a couple of years ago.

[Jim K]

yeah i once had a ready mixed 25litre? bucket of that stuff - that too lasted for years ;>)

Jim K

[GMM]

I'm by no means a plastering expert (for what it costs, I've been copping out and getting a real plasterer on the job when needed) but isn't the problem that you can't have everything? In this case, filling to any serious depth without cracking will always require a coarser material while a smooth finish needs a finer particle size. My guess is that if there was a good simple one-coat solution, all the pro plasterers would use it. If it's any use to anyone, my man uses hardwall to fill cracks and make deeper repairs and skims with finish. He reckons the secret to getting a good finish is to keep going over the surface at the right (difficult to define, though generally timed in ciggies and tea) points after applying it. Chatting with him (he hadn't counted before), he floats everything 7 times. Since watching him, I have thought about giving it a try again myself but for what he charges it never seems worth it, especially given the energy he puts into a day's work and it's always good to watch a skilled man work...

[SteveW]

I'll second that - I've not found anything as easy to finish for small repairs as joint filler. It feathers to nothing with no effort, and yes, it does remain useable for years.

SteveW

[Andy Champ]

I'm surprised to find (from the data sheet) that Artex, Gyproc and Thistle are _all_ brands of Saint-Gobain!

Andy

[Andrew Gabriel]

It's a compromise product.

For small quantities in chases/channels, you can use just finish coat plaster. For the undercoat, mix it up with a _little_ PVA, which makes it a bit like bonding coat. Use that, leaving space for finish coat. As this undercoat sets, it will crack badly, but this doesn't matter in this case, and simply gives you a good surface for the finish coat.

If you have an old (expired) bag of finish coat, it works really well for this because it sets quickly (which is normally a bad thing, unless you are doing just a small area, like refilling a chase).

[Broadback]

Thank you one and all for your excellent tips, I have taken great care to save it them for future use.

[js.b1]

One coat for bulk fill. Multi-finish skims fast, flat & smooth on top.

Multi-finish is not designed for bulk fill, cracks too severely if very dee= p.

Joint filler feathers better than multi-finish, it is meant to re tapered a= nd taped plasterboard joints. Trying to get one coat up to multi-finish sta= ndards is impossible because of time (even if it looks good, it would have = looked better with multi-finish for the same effort).