Stucco is a composition of slaked lime, chalk, and pulverised white marble tempered in water, designed to imitate different marbles used in the interior of buildings or monuments. Calcined plaster of Paris is also used. Although the plaster becomes very hard when properly calcined, it is too porous to admit of polishing it as marble. To remedy this, the plaster is wetted with glue or gum water, which, filling the pores, allows a polish to be given it. Some mix the glue with isinglass or gum arabic. Hot glue water is used for the solution of the plaster, as the want of solidity of the plaster demands that a certain thickness should be given to the works; to lessen expense, the body or core of the work is made of common plaster, which is covered with the composition just described, giving it about an inch in thickness. When the work is dry, it is polished in nearly the same manner as real marble. Pumice may be used. The work is rubbed by the stone in one hand, the other holding a sponge filled with water, with which the spot which has just been rubbed is instantly cleansed, to remove what has been left on the surface of the work; the sponge should be frequently washed and kept filled with fresh water. The marble is then rubbed with a linen cushion, with water and chalk or tripoli stone.

Willow charcoal, finely pulverised and sifted, is substituted for this to penetrate better to the bottom of the mouldings, water being always used with the sponge, which absorbs it. The work is finished by rubbing it with a piece of felt soaked with oil, and finely powdered with tripoli stone and afterwards with the felt moistened with the oil alone. When a colour is wished in the ground, add it to glue water, before making use of it to temper the plaster. When any particular marble is to be imitated, dilute with warm glue water, in different small pots, the colours of which are found in the marble; with each of these colours temper a little plaster, then make of each a lump nearly as large as the hand, place these lumps alternately one above another, making those of the prevailing colour more numerous, or thicker. Turn these lumps upon the side, and cut them in slices in this direction, instantly spreading them upon the core of the work, or upon a flat surface. By this means the design of the various colours with which the marble is penetrated will be represented.

In all these operations the glue water should be warm, without which the plaster will set too quickly, without giving time to work.

Wax Varnish To Preserve Statues And Marble Exposed To The Air

Melt 2 parts of wax in 8 parts of pure essence of turpentine. Apply hot, and spread thinly, so as not to destroy the lines of the figures. This varnish may be used upon statues which have been cleansed with water dashed with hydrochloric acid, but they must be perfectly dry when the application is made.