Plaster problems

[stealthwolf]

Tried to plaster a small section of the bathroom wall.

See this thread: //www.diynot.com/diy/threads/bathroom-plastering.465742/

Rubbed down the surfaces with sandpaper. Wiped away the dust. Applied 50/50 PVA and allowed to dry for 24 hours. Applied second coat and immediately mixed plaster (thistle multifinish). Applied first layer of plaster and let dry for 24 hrs. It started to have a crazy paving look but adhered well to the wall.

Following day I used the left over plaster in the bucket (still wet) and applied it. Smoothed it all. Looked really good.

Today, had a look and the second layer had the same crazy paving look but worse. It looked like the plaster was coming away from the wall. Managed to take off the chunks with my hands.

First layer:


second layer:


And today:



I am doing something very wrong here.

Am tempted to clear off the old plaster and use some ready mix.

Suggestions and advice would be welcome

 

[flameport]

Following day I used the left over plaster in the bucket (still wet) and applied it.

Plaster sets within 1 or 2 hours. If it is still usable the next day, there is something horribly wrong with it.

 

[Speedy23]

Plaster sets within 1 or 2 hours. If it is still usable the next day, there is something horribly wrong with it.

Wot I thought........are you sure it was plaster?

 

[stealthwolf]

Thistle multi finish was what I used. First time i've ever plastered

 

[flameport]

Thistle multi finish was what I used.

How and what was it mixed with?

 

[stealthwolf]

Used a bucket. Mixed with cold tap water and used a drill mixer attachment with my cordless.

First mix looked good - exactly like it should be but for some reason by the time I'd taken it upstairs, it had thickened to the consistently of buttercream icing ie very stiff.

Took a few more goes of mixing in water/plaster to get to the right consistency.

 

[flameport]

Setting too quickly is usually because the plaster is old or the bag has been left open.

If mixed plaster has already started to set, it's unusable and should be thrown away. It can't be thinned by adding water or anything else.

 

[John D v2.0]

Yes indeed, sounds like the plaster actually set in a few minutes due to not being fresh enough, and now you have set plaster dust mixed with water which wouldn't ever go hard.

 

[stealthwolf]

Thanks. The plaster was given to me by a friend who had some left over from earlier this year.

I'll retackle it again but ideally I need 10-12mm thickness. Is there something I can apply to make up the thickness rather than relying on plaster which I think made things worse?

 

[JohnD]

if your garden has a heavy clay soil, you can usefully throw the spoiled plaster on it. It will improve the texture for your plants when you fork it in. It is no good for anything else.

 

[John D v2.0]

Never use plaster unless you bought it yourself!
When we bought our house, the garage was full of junk and finish plaster that the seller was going to clear out. He offered the lot to me as he said it cost him a lot but I said no way. After a couple of months he suddenly came round with some guys and a van and they started removing probably about 25+bags of multi finish and other junk.
As they were loading into their van, the seller mentioned he'd spent the past couple of hours in the car park of selco trying to find someone to take it all away.
This was three year old multi finish from a damp garage as an inventive to take a load of junk to the tip!

 

[chappers]

You could bring it out with bonding and then skim over. But as your only really concerned about the couple of inches that will show in front of the bath panel and your inexperience plastering you may be better with something sandable like easifil. Wet the wall up a bit first to stop the dry backing sucking the moisture out too. This will reduce cracking. Build it up in at least two or three layers. and sand back.

 

[stealthwolf]

Well I had someone have a look and advised the two problems were probably dodgy plaster and leaving the radiator on in the room. The radiator's right next to the bathtub. The plaster looked fine when applied 9am and inspected around 7pm but the heating comes on at 7pm until 10pm, and comes on again 6am till 8am.

Will redo it but with fresh plaster and radiator off. Will look at easifil too.