In message , Moonshine
wrote
I've had a couple of goes at doing this with the same failed result.

Just trying to base coat plaster patch over some chased in channeling.

When going back to it in the morning it has all just shriveled up and
cracked like a wholemeal biscuit :-(

I've wet the surface before applying.

The house is warm with CH running - could it be drying out too quick?
Could the mix be too dry?

Am I using the wrong stuff - Blue Hawk Undercoat Plaster (which claims
to be non-shrinking!)?


Surrounding plaster sucking out all of the water in the new plaster. Try
'painting' the channel with a water/PVA mix to seal the surface - let
that dry - wet down the area and then plaster.

--
Alan