Sulphur is a favorite material with which to make easts of coins and similar articles. The process is as follows: -
Prepare the coin or other body of which the mold is to be made, by slightly oiling the surface; or if the body be made of plaster of Paris, the back of it is to touch the surface of water in a saucer or other convenient vessel, until the water just appears upon the surface, which will be known by its becoming more glossy. Then, having a sufficiently long strip of thick paper, from half an inch to an inch and a half in width, fold this round the coin; hold the paper between the thumb and fingers of the left hand, or if the medal should be large, or if a number are to be done at once, fasten the end of the paper with paste. Then melt by a very slow and gentle heat a little roll brimstone. When in a melted state, and while quite liquid, pour it steadily upon the coin. In a few minutes it will become crystallized into a seinitransparent mass, which may be removed from the coin or plaster cast, and will be found to be a fine and very exact counterpart of the original; and having plaster of Paris afterward poured into it, it will yield a very perfect impression.
Imitation coins may be made of sulphur by the following method: -
Prepare first the requisite molds of both sides of the coin by pouring plaster of Paris on each side alternately. Make a line, or other mark, on each mold, to show the position that they are afterward to be placed in, that the heads and devices may be in such a position relative to each other as they are in the original coin. Then melt the sulphur; - that is best which has been melted two or three times before, so that it has acquired a light brown color. When ready to pour, hold the two molds at the proper distance from each other, according to the thickness of the coin, and with the marks of both in line with each other, and wind round the edge of the molds a strip of card in such a manner that the card shall go very nearly round them, - a small vacuity only being left at the top. This being prepared, hold the card between the fingers and thumb, then pour in the sulphur, and as it shrinks, pour in more, until the space between the molds is full. It will immediately congeal, and when removed it will be found to have taken a fine impression from the molds, and to have all the sharpness of the original coin. When taken out it may be trimmed with a knife around the edges, for sulphur has the property of remaining soft for some considerable time after melting. To give the artificial coins clearness, and an appearance of antiquity, they must be rubbed all over with black lead, and then the black lead removed from the more prominent parts with a soft damp rag. A fine metallic appearance is given to medals by varnishing over the black lead surface with a weak solution of dragon's blood in spirits of wine, instead of partially rubbing the black lead off. The molds must of course be damped previously to using.