On the Working of Silver.
Having reached a most important and very interesting part of our subject, viz. the working of silver, and being desirous of making this treatise useful to the silver-worker in all the branches of his art, it is our intention to enlarge upon these processes—which are purely mechanical—and somewhat minutely to describe the various manipulations and arrangements required in the production of the wares of the silversmith.
After the removal of the bar of metal from the ingot mould, it should be plunged into a vessel of cold water, dried, and then carefully weighed. At this stage of the process it is ready for the operation of rolling. This process, so far as it concerns large ingots of the metal, is a distinct branch of the trade, and is carried on in separate premises established by certain firms for the purpose. These establishments are called “rolling-mills,” the machinery used in them (which is powerful and costly) being moved by steam-power, the reduction of the bars of metal to their various sizes is soon effected. The very thin ribbon-shaped metal is produced by submitting it to the action of rollers of smaller dimensions, one after the other, until the desired thinness is obtained. The bars of metal are taken to these mills by a man whose special duty it is to watch over them during the processes of rolling and annealing, otherwise it would be very easy to have an ingot of gold or silver exchanged for one of base metal, the mill companies not being responsible for the material intrusted to their care for rolling; hence the necessity for the porter’s services, to watch over his employer’s interests. To prevent accidentally exchanging the bars of metal, through their great similarity to each other, it is the usual thing for the men in charge of them to put a special mark upon the property of each person, previous to the process of annealing. This mark is applied by means of a piece of chalk or soap, and is not removable by heat. The annealing is performed in large iron muffles, heated to redness and kept in that condition by flues; the bars which require annealing being placed upon a piece of sheet-iron which slides into the muffle, and there they remain with the doors closed until they have become red hot. It is more particularly during this operation that each person’s property requires marking and watching, because of the number of bars admitted at one time into the muffle; and unless the greatest care be exercised at such a time some mistake is almost sure to occur.
A register is kept of the weight of the metal sent to the mill for the purpose of being rolled into the required shapes and sizes by the manufacturer, who afterwards works it up into different wares and utensils. The metal is also weighed on its admittance to the mill, by the clerk of the works, and again on its passage out, and a comparison of the weights registered; but in Birmingham, in some cases, this has been so irregularly performed that great discrepancies have actually taken place in the weights at times, and it has led to the establishment of another rolling-mill for gold and silver, in which the proprietors take upon themselves the whole responsibility and care of metals intrusted to their charge for the above purpose. The method pursued by them in respect to their business is as follows: A manufacturer sends a bar of metal to be rolled, carefully noting the exact weight and size to which it is to be reduced upon a proper order head. This weight is carefully tested at the mill, and if found correct, an invoice is given in exchange, upon which is entered the cost of rolling and the time when the work will be completed. The messenger then goes away, returning at the time stated to bring away the rolled metal.
The advantages this system presents over the others are obvious; the return of the full weight of the metal is guaranteed by responsible persons, the messenger is at liberty during the time occupied in rolling to follow his other duties, the weighing of the respective metals is far more accurately performed both in and out of the mill, besides greater satisfaction being given both to the manufacturer and the roller, the reciprocation of confidence between each, being among some of the additional advantages which might be enumerated. Messrs. Kemp, of Birmingham, deserve the thanks of the jewellery community for their enterprising efforts in the establishment of a system so admirably suited to the requirements of the trade.
The following table gives the charges at the present time for rolling bars of silver:—
Table of the Cost of Silver Rolling.
| oz. | oz. | £. | s. | d. | ||
| Under | 6 | 0 | 0 | 6 | ||
| Above | 6 | and under | 12 | 0 | 0 | 9 |
| ” | 12 | ” | 18 | 0 | 0 | 10 |
| ” | 18 | ” | 25 | 0 | 1 | 0 |
| ” | 25 | ” | 35 | 0 | 1 | 3 |
| ” | 35 | ” | 45 | 0 | 1 | 6 |
| ” | 45 | ” | 55 | 0 | 1 | 9 |
| ” | 55 | ” | 70 | 0 | 2 | 0 |
| ” | 70 | ” | 85 | 0 | 2 | 3 |
| ” | 85 | ” | 100 | 0 | 2 | 6 |
| ” | 100 | ” | 115 | 0 | 2 | 9 |
| ” | 115 | ” | 130 | 0 | 3 | 0 |
| Above this 2s. 6d. per 100 ozs. | ||||||
It is a usual thing at all rolling establishments to provide slitting-rolls for those who choose to avail themselves of that mode of cutting up their metal. These rolls are used for the purpose of cutting stout bars of metal into strips suitable for wire-drawing, thus dispensing with the older process of cutting with a pair of vice shears, which method was slow and somewhat uncertain in the production of good work. The slitting-rolls consist of circular barrels, after the manner of the “breaking-down” rolls, only of course much smaller in diameter, and with this exception, the slitting-rolls have square grooves cut into each barrel, the projecting portion of each corresponding with the hollow of the other, whereas the breaking-down rolls are perfectly smooth and plain. Rollers something similar to those we have described are used by wire-drawers to facilitate the speedy reduction of the metal, the difference being in the construction and action of the grooves. In the grooves of the latter, which are inserted farther apart, the hollows take a half-round shape, and unlike the slitting-rollers, during the revolution of the barrels, the grooves in this case directly meet each other, and thus produce a strip of wire almost round. It is almost needless to remark that wire-rolling requires some amount of practical knowledge to perform it properly. The manipulations indispensable to the art of silver working are so varied and so numerous that we are at a comparative loss which part of the process to consider first; however, if we follow the course of the workman with regard to the production of the various manufactures of his art, we shall perhaps not be far wrong in our desire to effect the purpose we have in view.