The walls are fine as they are – aren’t they? They certainly could be, but despite the fact this has all taken a long time, it will be fantastic when this is all finally finished!
The traditional covering of a straw wall is not surprisingly the same as the covering of a masonry wall – plaster. The only difference being conventional practise on masonry utilises cement, while a plaster for straw should be breathable. This breathability is the most desirable approach on any solid wall structure that pre-dates damp courses. Indeed the straw walls when plastered and lime washed, being close to two feet thick will actually look very much like the stone walls themselves.
The most commonly used breathable plasters employ lime as the binder, but there is an alternative; clay. You only have to look out of the back door of the pottery to realise there’s clay not very far away. The give away is the abundance of marsh grass that’s growing. In April 2011 we had the ditch across the back field cleared with a digger. Beneath about 8” of topsoil was revealed solid clay. When we saw it we couldn’t resist it we simply had to spread it on the straw walls!
A slip (liquid clay) coat was sprayed onto the straw first to provide a key for the next layer; the scratch coat. The plaster was made from clay which was dug from the ditch. It was slaked in water for a few days so it could be passed through a sieve made from ½” mesh to remove any stones and roots. The dug clay was naturally sandy so test panels carried out previously on the straw revealed that it had low shrinkage and was therefore not liable to crack. This meant that with a small amount of additional sand and plenty of chopped straw for tensile strength, a very good and sticky, usable plaster was made. The plaster was applied to the walls by hand – messy but fun! Once the scratch coat was dry a top coat without any chopped straw was sprayed on. The finished plaster was allowed to dry again and finally it was lime washed.
The resulting finish is both beautiful and practical. Solid walls of stone and straw painted white help to bring a calm ambiance to the pottery which is conducive to creative working.