MAKING OF WAX MOULDS. 53 



of Paris, wax, &c. by brushing over the surface with black lead. 

 It obliged the electro-metallurgist, however, to render himself expert 

 in the art of moulding, since no good electrotype can be obtained 

 without a perfect mould. We shall, for this reason, endeavour now 

 to give such instructions as will enable the student to make good 

 moulds after a very short practice ; but we need hardly add, that in 

 this as well as in every operation, however plain may be the instruc- 

 tions and easy the manipulations, practice is necessary to ensure 

 success ; so that the student ought not to lose patience should his 

 first attempt not succeed to his wishes. The substances used for 

 taking moulds from objects to be copied by electrotype are bees' 

 wax, stearine, plaster of Paris, and fusible metal; recently, gutta 

 percha has been very successfully used. The articles to be copied 

 are generally composed either of plaster of Paris or metal. Suppose, 

 in the first place, the article to be copied is of metal, and a mould 

 is to be taken from it in wax or stearine. The latter we have not 

 found to answer well, alone : when used it should be mixed with 

 wax, about half-and-half. 



Preparation of Wax. Whether the bees' wax have stearine in it 

 or not, it is best to prepare it in the following manner : Put some 

 common virgin wax into an earthenware pot or pipkin, and place it 

 over a slow fire ; and when it is all melted, stir into it a little white 

 lead (flake white) say about one ounce of white lead to the pound 

 of wax ; this mixture tends to prevent the mould from cracking 

 in the cooling, and from floating in the solution: the mixture 

 should be re-melted two or three times before using it for the first 

 time. 



To take Moulds in Wax. The medal to be copied must be brushed 

 over with a little sweet-oil ; a soft brush, called a painter's sash tool, 

 suits this purpose well : care must be taken to brush the oil well 

 into all the parts of the medal, after which the superfluous oil must 

 be wiped off with a piece of cotton or cotton wool. If the medal 

 has a bright polished surface, very little oil is required, but if the 

 surface be matted or dead, it requires more care with the oil. A 

 slip of card-board or tin is now bound round the edge of the medal, 

 the edge of which slip should rise about one-fourth of an inch higher 

 than the highest part on the face of the medal : this done, hold the 

 medal with its rim a little sloping, then pour the wax in the lowest 

 portion, and gently bring it level, so that the melted wax may 

 gradually flow over ; this will prevent the formation of air-bubbles. 

 Care must be taken not to pour the wax on too hot, as that is one 

 great cause of failure in getting good moulds ; it should be poured 

 on just as it is beginning to set in the dish. As soon as the com- 

 position poured on the medal is set (becomes solid), undo the rim, 

 for if it were allowed to remain on till the wax became perfectly cool, 



