CHAPTER V. (XII.)
Concerning Steel Dies for making Medals of bronze or other metals and how the latter are formed from these metals and from Oriental Stones and Cameos.
§ 70. The Fabrication of Matrices for Medals.
The craftsman who wishes to make medals of bronze or silver or gold after the manner of the ancients, must first with iron punches work in relief the faces of steel dies of which the metal has been softened piece by piece in the fire; as for example, the head alone in low relief, in a single steel die; and so with the other parts which are joined to it. Fashioned thus of steel, all the dies needed for the medal are tempered by fire; and on the block of tempered steel, that is to serve for mould and matrix of the medal, the artist proceeds to imprint by means of hammer strokes the head and the other parts in their proper places. And after imprinting the whole, he diligently smoothes it and polishes it again, giving finish and perfection to the said mould that has afterwards to serve for matrix. Many artificers have been in the habit however of carving the matrices with wheels, just as intaglio work is done in crystals, jaspers, calcedonies, agates, amethysts, sardonyx, lapis lazuli, chrysolites, cornelians, cameos and other oriental stones; and the work done in this way makes the matrices more sharp, as is the case in the aforesaid stones. In the same way they make (the matrix for) the reverse of the medal, and with these two, the matrix of the head and that of the reverse side, (trial) medals of wax and of lead are struck. These are moulded afterwards with a very finely powdered earth suitable for the purpose; and in these moulds, when the wax or leaden (trial) medal has been taken out, and they are pressed together in the frame, you may cast any kind of metal which pleases you for your medal.
These casts are then replaced in the steel matrices that correspond to them and by force of screws or wedges and with hammer blows they are pressed so tightly, that they take that finish of surface from the stamp that they have not taken from the casting process. But coins and other medals in low relief are stamped without screws, by blows of the hammer struck by hand.[[181]]
§ 71. The Cutting of Intaglios and Cameos.
Those oriental stones that we spoke of above are cut in intaglio with wheels by means of emery, which with the wheel cuts its way through any sort of hardness of any stone whatever. And as the craftsman proceeds, he is always testing by wax impressions the intaglio which he is fashioning; and in this manner he goes on removing material where he deems it necessary, till the final touches are given to the work. Cameos however are worked in relief; and because this stone is in layers, that is white above and dark underneath, the worker removes just so much of the white as will leave the head or figure white on a dark ground. And sometimes, in order to secure that the whole head or figure should appear white on a dark ground, he dyes the ground when it is not so dark as it should be. In this art we have seen wondrous and divine works both ancient and modern.