168 PKACTICAL TAXTDEEMY. 



secret of successful casting is in making tlie joints of the 

 molds at tlie proper places, and at correct angles, so that 

 they can be removed without the interference of shoul- 

 ders on the cast. In taxidemiic casting, tin, plaster, 

 wax, and glue are used ; and in modelling, clay, plaster, 

 composition, putty, and wax. 



In making but a single cast, particularly from flesh, a 

 full-jointed mold is not necessary. The object may be 

 braced in position with clay, and covered with plaster, 

 which should be thinly mixed, and allowed to thicken be- 

 fore it is placed about the form. The plaster should be care- 

 fully run or pushed under the object, and slowly ^^ built " 

 upon, until the whole is covered. Owing to the incon- 

 venient shape of some objects, they require to be turned 

 over to complete covering, When the plaster has ^^set" 

 hard and dry, saw the mold in two or more pieces, and 

 remove the contents. In casting, gi'ease the joints and in- 

 sides of molds ; tie together, and run them full of plaster. 

 If the sections of the molds do not part from the cast 

 when diy, chip them off in pieces, and if there be any 

 imperfections on the cast, restore them by modelling. 



In preparing molds for regular casting, it is necessary 

 to construct a single section at a time, making holes and 

 buttons in the joints to prevent the sections from slip- 

 ping out of position. . Molds of plaster ai'e generally used 

 for this kind of work. Though it is not genei-ally known, 

 glue molds, havmg plaster covers, can be used with fewer 

 joints, and with less inconvenience. Thin plaster runs 

 closely to glue-molds, which can be stripped repeatedly 

 from casts, without regard to shoulders and angles. 



Tin is run in molds of plaster in making teeth and the 

 connecting parts of the crania. The molds should be 

 warmed and well smoked to insure a good solid casting. 



Plaster can be run m molds of metal, plaster, composi- 

 tion, glue, wax, and wood. The sections must be correctly 

 jointed, however, or the cast will be broken in removing. 



