Page:The American Cyclopædia (1879) Volume IV.djvu/91

 CASTING 83 may either be taken in as many pieces as it is designed to make the bronze casting, or it may be cast in one piece, or in as few as possible and then joined together, leaving the bronze founder to make his selection of sections in which to take his loam mould. The method of proceeding to make a mould for a plaster sta- tue from a clay model is as follows : The model is made pretty wet, so that the moisture from the plaster will not be too much absorbed be- fore it sets. Then a mixture of plaster and water is spread over a certain selected portion of the statue, say the front half of the head and chest, a barrier of clay having been previously erected along the boundary line. After the plaster has set the clay barrier is removed, any injuries that may have happened to the back part of the head and chest are repaired, and the edges of the plaster soaped or washed with a mixture of clay and water. A plaster mixture is then spread over the back of the head and chest, the two applications encasing the whole body above the waist. The remain- der of the body may be taken in two or four pieces. If one limb is partially raised or much separated from the other, it may taken in two halves by itself; but if not, the lower part of the body and both limbs may be moulded in two pieces, one before and one behind. Very often one arm will be "taken with the chest, while the other pne will be taken separately. After setting, all the pieces may be removed, and of course some of the clay will be brought away with them; but that is of no consequence if the plaster mould is a good one, because, with care, a copy is now secured. After remo- val, the separate pieces are cleaned with water and the careful use of a brush. The pieces may then be put together and the different parts of the statue cast in the same manner as a bust is cast. Measurements have been taken from cer- tain points on the clay model to the dividing lines, and recorded. These points and lines are reproduced on the plaster casts, so that their edges may be cut to precisely fit each other and preserve the symmetry of the original mod- el. The statue is then completed by putting all the parts together and cementing them with plaster mixture, which is spread on over the seams on the inside by the hand, introduced through an opening made for that purpose, which is afterward repaired in the same way. If a bronze copy is to be taken and the bronze founder prefers to have the pieces separate, of course the joining will not be done. In cases where the statue is clad to the throat, there will be one additional piece of work to be per- formed to prepare it for the bronze founder, which is to detach the head, and add plaster in a conical form to the neck, which is to be fitted into a collar ; for the head should be cast sepa- rately in bronze, and the artist should separate it and fit it in its joint himself, so that the prop- er pose shall be preserved. A statue in bronze is cast in two or more pieces, generally in from four to six, the number of pieces usually be- ing in inverse proportion to the mechanical and technical skill of the founder. The principal difficulty in casting a statue whole is the crack- ing and straining of parts on cooling and con- traction of the metal. If, however, this can be cast very thin, and uniformly so in every part, avoiding masses where there are folds of dress or any irregular surfaces, no cracking may oc- cur. It is not always, however, desirable to avoid division, because the parts may be skil- fully joined and much tedious labor saved. In the case of such a work as the statue of Pallas, shown in fig. 23, the whole figure, with the ex- ception of the right arm and upper part of the spear, which are to be removed, may be cast in one piece. If of plaster, we will suppose the model to have been varnished with a solu- tion of shellac in alcohol, previous to which it may have been painted with linseed oil and dried, to harden the surface ; but this may have been omitted. The statue is laid upon some very fine loam in the iron flask in which it is to be cast, and well adjusted in abed prepared for it, which fits its surface perfectly, giving a firm support. A quantity of fine loam, which is only to be obtained in a few localities, possessing peculiar physical properties, adhesive and yet porous, after having been ground several times in a mill resembling a sugar mill, is take,n in small quantities at a time and pressed and ham- mered into compact sections upon the surface of the model. Each section must embrace such parts as will allow of its being drawn. The process is similar to that of making a piece mould with plaster of Paris, except that the mate- rial in the latter case is spread on in a plastic con- dition, while the former is ram- med and ham- mered on. The process is a very difficult and te- dious one, re- quiring several weeks and some- times months to make a mould for a life-size statue. In Ger- many a compo- sition is used ""innmiiimii' ' '"I"' .ii.M^. - v J FIG. 22.-Piece Mould for a Statue. whl ^ 1S S P re. ad on like plaster and allowed to harden. Whatever material is employed, the problem is to fit together firm but