2537. Fruit, &c., in Wax
For the imitating of fruit in wax, very different rules are to be observed. The following directions may, however, be generally followed:
The material of which moulds for waxen fruit should be composed is the
best
plaster of Paris, such as is used for plaster casts, &c. If this cannot be procured, the inferior plaster, from the oil-shop, may be substituted, if it can be obtained
quite fresh
. If, however, the plaster is faulty, the results of the modelling will of course be more or less faulty also. It is the property of plaster of Paris to form a chemical union with water, and to form a pasto winch rapidly "sets" or hardens into a substance of the density of firm chalk. The mould must therefore be formed by impression from the object to be imitated, made upon the plaster before it sets.
2538. Causes of Want of Accuracy
The use of an elastic fruit in early experiments leads to a want of accuracy in the first, steps of the operation, which causes very annoying difficulties afterwards; and therefore a solid, inelastic body—an egg boiled hard—is recommended as the first object to be imitated.