In architecture it would definitely feel good to have spaces which have a natural feel to them. In order to achieve such spaces one should finish the space off with plaster walls. A variety of expressions of walls are created through combinations of lime, clay, cement, sand, fibers, glue and so forth. Lime is an effective material in airtight spaces. It hardens through the absorption of carbon dioxide. 1B clay controls the humidity in the air. By combining a variety of ingredients into these materials, and through timing, sense, and control of the iron, it is possible to give the walls expressions.