Plastering tips?

[Matthew]

Hi All,

Quick question for you regarding plastering technique. I have a room with a number of chased runs containing electrical conduit that I need to plaster. They are a couple of feet long and about 4 cm deep. I tried to fill one last night but by the time I was half way along the plaster I had mixed had dried out. Is there any easy way to extend the time plaster take to set to buy me maybe another 30mins or so? I was surprised to see how quickly it went off! I think also the fact that I mixed too much in one go probably didnt help.

Thanks, Matthew

[Christian McArdle]

Make sure the plaster is new. Old plaster goes off very quickly. Covering up a chase would only take a couple of minutes, so you should be able to do loads during the working time of the plaster.

Assuming the plaster was good, then your alternatives are to work quicker or mix less plaster at a time.

Christian.

[noelogara]

brush on lots of water into the chased groove first.

[daddyfreddy]

Over mixing can cause it to harden sooner too. Get the freshest plaster possible and only make as much as you can work with. I buy plaster from Wickes as they always have new stuff.

[Stuart Noble]

You can't really do this in one operation. Fill to the surface roughly with whatever plaster you have kicking around (although undercoat or bonding is better), then skim with finishing plaster or filler when dry. Best to pva seal the brickwork first

[Cordless Crazy]

Dry brickwork will suck the moisture out of you plaster well quick. Ge one of those plant spraying thingys and spray the chase good and prope before plastering.

Check the used by date on your bag of plaster. Normally only has a month life, and if it has been siting in the DIY store for a long time it could have been dead well before you bought it

-- Cordless Crazy

[Christian McArdle]

Oh, and lime mortar sets much more slowly, but might not be appropriate.

Christian.

[John Rumm]

Don't under estimate how much either! old plaster sucks the water straight out of the new stuff and makes it unworkable very quickly.

I use one of those pump up garder sprayers to give it a good wetting down, leave it for a min to soak in a bit and then plaster.

[The3rd Earl Of Derby]

Try PVA instead of water,too much water in the old plaster will cause weakness of the plaster and eventually crack at the chase edges.

[The3rd Earl Of Derby]

Try slapping in the same plaster half the depth then wait 20/30 minutes then finish off with same plaster to bring it level. No need for dry wall plaster where chases are concerned.

[Christian McArdle]

Personally I use one coat plaster for this. Gets the job done in one operation without the problem of recessing the bonding and mixing another load of plaster for the surface.

Christian.

[Christian McArdle]

Personally I use one coat plaster for this. Gets the job done in one operation without the problem of recessing the bonding and mixing another load of plaster for the surface.

Christian.

[Stuart Noble]

Always shrinks a bit though. If you can get the finish perfect first time, hats off to you

[Gav]

ok here we go, i assume you are just using finnishing plaster(it is better to rough/bond first with bonding or roughing plaster prior to skimming/finnishing) if you are using water near electric, switch them off first. soak the area with water, then appl some plaster all the way along to form a primer or base coat, not to fill the chase, then go bact to start and fill in the chase, this should help to stop it falling out and make the job easier and thus faster! if you want you can do this in two stages, just remeber the top coat needs to be wetter/sloppier than the bottom coat or it will pull it off! hope this helps

[daddyfreddy]

That's the beauty of one coat, not only does it fill deep in one go it also doesn't shrink like normal bonding.

[Andrew Gabriel]

Do you mean dried out, or set? Two completely different things, with different solutions.

Yes, I keep old bags of plaster specifically for such things. It's very useful to be able to slap it in and have it all polished off in 10 minutes.