The interior plaster is done (everything but a few spots around the doors), so now it’s onto the next phase–the alis (or aliz) to smooth over the earth plaster.
Like all plasters, first thing is to come up with a recipe. Every bit of sand and clay acts differently. We picked up some kaolin clay from New Mexico Clay in Albuquerque, which gives us a white clay to play with for the bathroom. And this was mixed with a white sand (pool sand) that was screened to make a very fine sand. The mix is a little more sand to clay, in about a gallon of water–you want something that looks like a thick milkshake (or really heavy cream). This is painted on, and then when it’s dry to the point of a leather-like feel, you rub it with a damp sponge to put a hard coating on it (taking off some of the sand). In addition, wheat paste is used to help the alis bind–in this case, a quart of wheat past for every gallon of water. The wheat paste is made from one cup of cold water and one cup of flour mixed, and then added to one cup of boiling hot water–this is made up usually in quart quantities, so it’s four cups cold water mixed with four cups flour, and this is added to four cups of boiling water–it’s only kept on the stove until it turns translucent, which doesn’t take long at all.
The “painting on” process for the alis makes it a lot of fun to apply–it’s far less work intensive than the plaster work. The key here, too, for the smoothing or polishing phase is not to let it dry too much–the dryer it is, the wetter the sponge has to be, and the more elbow grease needed to smooth it. So it’s best to do the alis bit by bit (in other words, apply and then smooth that same day, then work on the next bit of wall the next day).
The last stage for the bathroom will be to apply BioShield wall glaze–this is going on only in the bathroom, since we need a little more protection from water here. The BioShield will give a harder glaze (the other rooms are finished with linseed oil to keep the “dusting” down).
For the other rooms, we’re going to try a mix of various pigments to see how these work in both our local clay, and with the kaolin clay. It’s all about experimenting to see what works best. And if you don’t like the results, don’t worry. The next coat can cover up all the mistakes.