Plaster cast composition

When I came to, I was so tremblingly afraid of my own insanity that I wrote Night and Day mainly to prove to my own satisfaction that I could keep entirely off that dangerous ground. I wrote it, lying in bed, allowed to write only for one half hour a day. And I made myself copy from plaster casts, partly to tranquillise, partly to learn anatomy. Bad as the book is, it composed my mind, and I think taught me certain elements of composition which I should not have had the patience to learn had I been in full flush of health always. L4, p. 231)... 

In 1844, Franc in formed a series of casts in plaster composition, in imitation of ivory and, in 1846, the Society of Arts in London awarded to him a prize. 

Following Jabir, and with almost his skiU and later reputation, was the Persian alchemist Al-Razi (c. 850-c. 925), known to Europeans later as Rha-zes. He, too, carefully described his work, preparing plaster of Paris, for instance, and describing the manner in which it could be used to form casts holding broken bones in place. He also studied and described metallic antimony. To mercury (which was volatile—that is, would form a vapor when heated) and to sulfur (which was inflammable) he added salt as a third principle in the composition of solids generally, for salt was neither volatile nor inflammable. 

There are several factors in slip casting method. The porosity of the plaster mould is controlled by water content. The particle size of the powder should be relatively coarse to permit high level of vehicle permeability through the cast wall. Slip casting is widely used commercially because it enables the casting of complex shapes from an almost unlimited variety of ceramic composition, at a low cost. The most disadvantage of this process are low production rates and relatively short life of mould. 

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