Heritage plaster is cracked in small areas - help?

[Socksitis]

Hi,
plastering is getting there, I am ow on the Heritage top coat, but in some places it is cracking - only small cracks, I think I know why on some areas, but would appreciate any advice.
I think where there is a change in new lime plaster underneath to old lime with DG27, the join is cracked in places. We wetted and scoured with the sponge again and all appears ok now.
Is it something I am not doing though - perhaps it is too thick in a place or to or not scoured and compressed with the sponge, or not pushed on enough with the float?
Look forward to the advice

 

[skier-hughes]

drying too quickly? keep it damp and trowel the cracks away.

 

[malcolm]

Normally cracking is a result of shrinkage as the lime dries. A cheat is to apply the plaster, let it dry for a couple of hours, then go over it again hard with a trowel. I tend to cheat even further as my plastering isn't very good - let it dry a couple of hours, go over with a wood float to flatten it, trowel, sponge a little, then trowel again to a smooth finish.

Rapid movement of water tends to increase cracking, so a well sprayed wall before plastering and spraying the plaster for a couple of days after seem to help.

 

[livias]

Could be that tbe old is very dry and the new is not so dry. When you wet the wall make sure the old is well wetted
... oo see that i am 3the third person to suggest that ☺

 

[88v8]

And here's the fourth...... the background must be damped. Not just a vague splish with a trowel dipped in a bucket. A hand sprayer for small areas, a pump-up sprayer for larger work. Not awash of course. But damp.

Watched a lime plasterer working in a cottage refurb. He had a sprayer, was wetting the finish coat, and trowelling, wetting and trowelling. Just a mist. A few hours later returning from our walk he was still misting and trowelling the same wall.

It's not a finish-and-pack-up job like gypsum.
Lime takes time.

Ivor

 

[livias]

I tend to get it awash, leave it 20 minutes, then spray again, to a damp but not awash level

 

[Socksitis]

Thank you one and all. I will spray more. It is not the whole wall, just small areas, especially the corners (internal) which could be where the spray does not reach well enough. I do tend to spray several times before I start plastering. But maybe I need to spray during plastering. One area I think has a lot to do with the substrate - not as it appears! It may well come off, will need to re do differently.
I did consolidate some I did 2 days ago with the float a little while after plastering - the thing is these float coats do go off quite quickly.

 

[skier-hughes]

and spray regularly a fine mist as it is drying, I do mine for days, several times for the first few days until it's once and then a few days of drying before either I wet again in readiness for next coat, or after top coat just leave and if no problems continue to leave to dry.