Roman techniques of manufacturing silver-plated coins

Almost since the invention of coinage, imitation silver coins have been manufactured by attaching a silver layer, with the same composition as the contemporary official coinage, on to the surface of a base metal core. In the case of copper cores, this process could be carried out by coating the surface of the core with a layer of solder consisting of a silver–copper alloy, or by attaching a layer of silver foil to the surface, either by soldering or by heating to form a layer of eutectic at the interface of the silver and copper. This latter technique is, in effect, a self-soldering process which is known today as Sheffield plating. In the case of iron cores, however, the self-soldering process could not be used, and silver plating had to be carried out either by using hard (i.e. silver–copper) solder alone or by soldering silver foil to the surface of the iron.

In the Republican and early Imperial periods, a common technique of manufacturing silver plated forgeries was by the application of silver foil, but after the debasement of the official silver coinage, which began at the end of the 1st century AD, plated coins with a high purity silver layer on the surface are not usually found. Instead, the forgers used hard solder coatings for the blanks.