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Second coat mixing and application

We used exactly the same method for mixing the plaster, though with a bigger mixing pit, so we could make bigger batches and have more people in the pit.

We wetted down the walls with a mister attachment and hose, repeating when the moisture gets sucked away by the dry clay and then applying slip just before the plaster to have double security of the first and second coats bonding. There should be plenty of cracks and poking out bits of straw to create mechanical bonds as well.

During this coat we went jute scrim/ burlap crazy! We had quite a number of big cracks, particularly around the timber framing and joins of bales, so we filled them in, adding extra straw if really big and used slip to glue patches of burlap to them and then plastered over, the cracks weren’t a problem when the second coat dried, so it must have worked! We also wrapped burlap over some of the corners of the walls where there might be more likelihood of damage and high traffic, using slip as a glue. We mainly did this after applying the second coat, but in some areas we had jute scrim sandwiches with the second coat as the filling.

This coat is for shaping the walls. We used our hands to apply it, this time, the focus was not on working it in, and pushing, but putting the energy into smoothing and building the shapes. Again, we tried not to do layers that were really thick in one go. We’re quite happy with the results but in hindsight, using a long derby float at this stage with spirit level checks would have helped get a flatter result, if you’re into that kind of thing.

We were going for simple walls with a few curved reveals, but with clay plastering there are lots of possibilities to get creative and make interesting shapes. This is the time to do any sculpting etc, using extra straw/ fibres to build up the shapes.

You can score the plaster with a knife to help the final finish coat bond to the second coat, which is easier done when the plaster isn’t dry, but not slick with surface water either. We did this on the inside coat and didn’t bother on the outside. Our finish coat seemed plenty sticky enough either way, so the scoring may have been a waste of time, but it isn’t too big a task if you want extra peace of mind.

Same applies in terms of drying out, we went through more wheat and mould growing – all good :)