CAST 9, 



619 



drawn. If the cavity be of an irregular figure 1 , the 



^-*"^ con- may consist of day al-.o su.spt. ruled within the 



mould by cross wires, or otherwise, and afterwards 



picked out by a sharp pointed or hooked implement. 



In casting a has relief from wax, or to obtain ano- 

 ther cast of the same substance, the figure d<-M; 

 first to be modelled on wood or glass, and being sur- 

 rounded by a frame, plaster is poured over it. This 

 is allowed to dry, and when removed, serves to 

 receive the cast. If dipped in water, and suddenly 

 withdrawn, the wax poured in will not adhere, and 

 comes out quite clean. 



Delicate and beautiful casts arc obtained in sul- 

 phur, which, of late years especially, has been suc- 

 cessfully employed to preserve representations of the 

 most elegant sculptures of antiquity. The mould 

 for a cast of this description being formed of plas- 

 ter, is repeatedly dipped into half a pint of boiled 

 lintseed oil, mixed with an ounce of spirit of tur- 

 pentine, by which the surface is hardened. A quan- 

 tity of sulphur being melted in an iron ladle over the 

 fire, and allowed to flame for five or six minutes, ia 

 taken off, and after cooling a little, is poured into 

 the mould; and the cast having stood a few minutes, 

 may be taken out. Adding a third part of vermilion, 

 and stirring the mixture well together, will produce 

 a cast of a fine red colour. When the cast is taken 

 from the mould, it should receive a polish, from being 

 rubbed over with clean cotton. 



Small metallic casts were easily obtained from 

 moulds of plaster, clay, or sand, the latter of which 

 are preferable for those of larger size. In all cases, 

 particular care must be observed to have the mould 

 perfectly dry, otherwise the cast will be disfigured 

 by blow- holes or pores, and the safety of the artist 

 endangered by explosions, from the rarefaction of 

 the fluids remaining unexpelled. Yet as very few 

 casts of considerable size are to be obtained free of 

 blow holes, these must necessarily be tilled up, either 

 by screwing in a portion of the same substance, or 

 beating it in. The latter is the better method, as 

 the interstice is more completely filled up ; but in- 

 stead of simply filling up the pore in the cast taken 

 from the mould, the defect is more completely cured, 

 by enlarging it somewhat more, and then beating in 

 a piece of metal. If the cast has to undergo a con- 

 siderable change after coming from the mould, it 

 should be beat ovtr the whole surface with a hammer 

 of a few ounces weight, which will close all the small 

 blow-holes, and fit it for receiving a suitable polish. 

 This method cannot be adopted where a complete 

 and perfect figure from the mould is desired. 



Equal quantities of pumice-stone and plaster of 

 Paris, with a third of clay, is considered a suitable 

 composition for moulds to receive small metallic casts ; 

 or two parts of fine brick-dust, added to four of 

 planter, and mixed up with water until of the con- 

 sistence of cream. Supposing a small animal, a 

 bird, frog, or lizard, is to be imitated, the sub- 

 ject, after being moistened with spirit of wine, is 

 to be suspended by threads, in a trough or frame, 

 which must then be filled with the composi- 

 tion. But a channel to the cavity which the sub- 

 ject occupies must be preserved by a strong thick 

 wire, proceeding from its extremities, to above the 

 surface of the composition. This, when withdrawn, 

 will leave a conduit for receiving the metal. Other 



vents are necessary, in all moulds, Urge or small, for 

 allowing the included air to escape. The bubj-ct 

 thus remaining included, and the wire* being with* 

 drawn, th< mould must be gradually exposed to suc- 

 cessive degrees of heat, until becoming red hot, 

 when -by the subject will be totally consumed, and a 

 cavity left, corresponding to the space occupied by 

 its parts. But as some particles of dust or ashes 

 may remain after every precaution to discharge them, 

 the cavity should be filUd with mercury, by which 

 means they will rise on the urface, and may be pour- 

 ed out along with it. The mould, when converted 

 to use, must be rendered very hot, and gently struck 

 after receiving the metal, that acces. may be gained 

 to all its partn, and the expulsion of air facilitated. 

 After being allowed a sufficient time to cool, the cast 

 is removed. 



Metallic casts of large subjects, are great and im- 

 portant works, wherein the concurrence of many 

 different circumstances are essential to the success of 

 the artist. The ancients were well acquainted with 

 the various methods practised in casting in bronze, 

 as appears from the beautiful relics still preserved to 

 us, and the description of the busts and statues of 

 divinities in their temples. It has been conjectured, 

 however, that none of them were of extraordinary 

 size ; that they were in general little if any larger 

 than life, and that the colossus, celebrated as one of 

 the wonders of the world, could only have been form- 

 ed of plates of metal. S;me of the moderns have 

 peculiarly excelled in this branch of the arts, and have 

 themselves minutely laid down the rules whereby to 

 obtain a successful metallic cast. 



Here, as in all other cases, a model of the cast is 

 built on a skeleton, composed of wood or iron, ex- 

 hibiting the angles and curvatures of the figure de- 

 sired. The famous artist, Benvenuto Cellini, affirms, 

 that this skeleton should be covered, to nearly the 

 size of the figure, with clay, well beaten together 

 with a quantity of rags, by an iron rod, and the mix- 

 ture thus kept several months to macerate. It will 

 then form a paste, which may be wrought up 

 with the hand, and is fashioned into shape. When 

 sufficiently baked, and having been allowed a con- 

 siderable time to dry, that no contraction may ensue 

 on subsequent heat, this rude resemblance of what 

 is to be cast is covered with a coating of wax, not 

 less than an inch thick, on which the artist impresses 

 the exact form of what the cast is meant to exhibit, 

 and varnishes over the surface. A mould is next pre- 

 pared of plaster, or of a mixture of clay and sand, 

 which it is exceedingly difficult to procure of suitable 

 quality, and from this cause the works of skillul sta- 

 tuaries have failed ; and being applied around the 

 model, is allowed to become perfectly dry. This 

 mould, it is evident, is to receive the cast, but a dif- 

 ferent proceeding from taking it to pieces is employ- 

 ed to obtain a cavity. It is perforated by innumer- 

 able channels through the clay to the surface of the 

 model, which also are all filled up with wax. The 

 greater the number, the more is the chance of suc- 

 cess. 



When the model is thus completed, and surround- 

 ed by the mould, it is lowered down into a pit, by 

 means of a cram , and a brick wall, capable ot re- 

 sisting considerable pressure, built around it. There 

 it is exposed to a moderate degree of heat, by which 



Cart*. 



