Lime plaster on magnesium board

The first areas we plastered were in Mike Wye 3/2 lime plaster, which we had some problems with (as already discussed).  The next plaster we tried was site mixed lime plaster.  We mixed this 1:1

Lime putty and

Kiln dried sand.  This sand is slightly courser than the sand used in the Mike Wye plaster and seems to go on the boards slightly better.  We are still having trouble getting over the beads and the plaster is still not drying as evenly as it could.  One theory is there are very slight undulations in the board which mean the thickness of the plaster varies very slightly.  We are also getting some shrinkage cracks as it dries out.

Plastering begins!

At last we have started plastering!  We are starting with lime plaster - premixed from Mike Wye 3/2 mix, which is what we used for the test many months ago now.

The corner beads and stop beads are fitted, ready for the plaster.

Unfortunately it hasn't started as smoothly as we had hoped!  Despite the test being successful back in May we are finding that the lime plaster is going off very unevenly on the boards and the time taken to go off varies massively from board to board.  It is particularly bad around the beads.  This makes it difficult to trowel the plaster off and difficult to judge how much to put on, as it would be a disaster if it all went off at the same time and couldn't all be finished properly.

The first finished room looks good and feels really silky.  We are working with our plasterer to find a way to make the job quicker and easier.  He has tried adding more fat lime putty to the mix, which has helped a bit.