On Wednesday this week, we decided to put the finish coat of plaster on the walls above the open, center section of the house. I wanted to get the scaffolding out, and we needed it for doing these walls.
I purchased some wheat paste from Natural Craft Supply the previous week which arrived this week. I can make my own wheat paste for less money using high-gluten white flour, but the product I bought is easy to use and works well. The idea with the wheat paste is that it works as a binder in the plaster. Basically, it’s a glue made out of flour (traditionally, it’s been used to glue wall paper to the wall). It helps to hold the plaster together more strongly and keeps the surface from dusting off when it’s dry. It works, too.
Our recipe for the finish plaster was to screen 5 gallons of sand through a window screen (it is amazing how many rocks can be screened out of sand). Then, we mixed in 3.25 gallons of dry, powdered, white kaolin clay by hand. Once that was mixed, we mixed in 1.5 pounds of wheat paste (about 3 cups of dry powder). The next step was to add water and mix thoroughly. It’s amazing how much water it can absorb – about 4 gallons.
We found that it is easiest to smear the plaster on with your hands after dampening the wall (we use a garden sprayer) and then trowel it as smooth as possible, adding or removing material as necessary. After the plaster has begun to set up a little as it begins to dry, I came back over it with a pool trowel to take out trowel marks from the previous step. I tried buffing it with a yogurt container lid, but I liked the trowel better.
The plaster looks gray when it’s wet, but it dries to a white color. Later, I will mix up an alis to paint the walls with. An alis is a clay-based paint (clay, fine silica sand, wheat paste, and water). This will help even out the color (white because we’re using white clay – I’m not intending to put in any pigments) and seal up the finish coat a little more.
Yesterday, the boys and I straightened things up in the house and swept the floors. We also removed the scaffolding from the center of the house. I took a few photos to share.
The photo below is one from three that my camera stitched together – the beams are not really curved like that.