The manufacture of Sheffield plate was made possible by the discovery in 1743 that plates of silver and copper could be fused together to form one indivisible sheet of metal. Thus, an article could be manufactured exactly similar in external appearance to one of solid silver, but from material costing far less. The inventor of the process was a Sheffield cutler, Thomas Bolsover (1704-88).
For some years only small articles were made, but by 1760 production had increased and bigger pieces were attempted with success. Later, it was found possible to plate an ingot of copper on both sides, and it was then no longer necessary to coat the inside or underside of an article with tin; which had been done hitherto. As methods had been devised already for concealing the red line of copper showing where it was cut on an edge, the resemblance to silver was very close. The deception was aided further by the fact that some makers marked their wares with stamps that could be confused easily with those on silver.
Production of Sheffield plate received a fillip when a duty of 6d an ounce was levied on silverware in 1784, and again in 1815 when the duty was raised to 1s 6d an ounce. The ware was made in quantity between 1780 and 1830 and a surprisingly large amount has survived. After 1830 little was made, and then began the plating of silver on a base of German silver (an alloy which showed silvery when the outer coat of real silver wore through). Finally, in 1838 this was superseded by the introduction of electroplating.
Genuine Sheffield plate in good condition is scarce; in the course of time the coating of silver has often worn away in places and the copper is revealed clearly. When this happens the piece can be given a fresh coat of silver electrically, but the colour and texture of the old cannot be reproduced. Once Sheffield plate has been tampered with in this way much of its value has been lost for ever, and the careful buyer will not want to add such specimens to his collection.