CHAPTER VII.[D

Silver Solders: their Uses and Applications.

[D] See observations on Depreciation of Cost Price of Silver in Preface to Fourth Edition (pp. vii, viii), and the new Table of Cost Prices of Alloys in this Chapter, following the Preface (p. x).

Soldering as applied to silversmith's work is an art which requires great care and practice to perform it neatly and properly. It consists in uniting the various pieces of an article together at their junctions, edges, or surfaces, by fusing an alloy specially prepared for the purpose, and which is more fusible than the metal to be soldered. The solder should in every way be well suited to the particular metal to which it is to be applied, and should possess a powerful chemical affinity to it; if this be not the case, strong, clean, and invisible connections cannot be effected, whilst the progress of the work would be considerably retarded. This is partly the cause of inferior manufactures, and not, as frequently supposed, the want of skill in the workman.

The best connections are made when the metal and solder agree as nearly as possible in uniformity, that is, as regards fusibility, hardness, and malleability. Experience has proved, more especially in the case of plain and strong work (or work that has to bear a strain in the course of manufacture), that the soldering is more perfect and more tenacious as the point of fusion of the two metals approaches each other; the solder having a greater tendency to form a more perfect alloy with the metal to which it is applied than under any other conditions. The silver or other metal to be operated upon by soldering being partly of a porous nature, the greater the heat required in the fusion of the solder the more closely are the atoms of the two metals brought into direct relationship; thus greater solidity is given to the parts united, and which are then capable of forming the maximum of resistance. It is thus obvious that tin should not be employed in forming solders possessing the characteristics we have just described, for being a very fusible metal it greatly increases the fusibility of its alloys; but when very _easy_ solder is required, and this is sometimes the case, especially when zinc has been employed in the preparation of the silver alloy, its addition is a great advantage when it comes to be applied to the work in hand. Solders made with tin are not so malleable and tenacious as those prepared without it, as it imparts a brittleness not usually to be found in those regularly employed by silversmiths; for this reason it is advisable to file it into _dust_, and apply it in that state to the articles in course of manufacture.

The best solders we have found to be those mixed with a little zinc. These may be laminated, rolled or filed into dust; if the latter, it should be finely done, and this is better for every purpose. Too much zinc, however, should not be added under any conditions, as it has a tendency to eat itself away during wear, thus rendering the articles partly useless either for ornamental or domestic purposes earlier than might be anticipated. Solders thus prepared also act with some disadvantage to the workman using them, for they possess the property of evaporating or eating away during the process of soldering, leaving behind scarcely anything to indicate their presence; consequently the workman has to keep on repeating the process until the connection is made perfect, which is always done at the expense of a quantity of solder as well as loss to the workman as regards time.

Solders made from copper and silver only are, generally speaking, too infusible to be applied to all classes of silversmith's work.

Solders are manufactured of all degrees of hardness; the hardest of all being a preparation of silver and copper in various proportions; the next being a composition of silver, copper, and zinc; and the easiest or most fusible being prepared from silver, copper, and tin, or silver, brass, and tin. Arsenic sometimes enters into the composition of silver solders, for promoting a greater degree of fusion; and we have heard of workmen actually refusing to work with any other solder. The employment of arsenic has, however, a tendency to slightly endanger the health of those persons using it in large quantities; and of late its employment has not been persevered in.

In applying solder of whatever composition it is of the utmost importance that the edges or parts to be united should be chemically clean; and for the purpose of protecting these parts from the action of the air, and oxidation during the soldering process, they are covered by a suitable flux, which not only prevents oxidation, but has also a tendency to remove any portion of it left on the parts of the metal to be united. The flux employed is always borax, and it not only effects the objects just pointed out, but greatly facilitates the flow of the solder into the required places. Silver solder should be silver of a little inferior quality to that about to be worked up. The various degrees of fusibility of the several solders are occasioned by the different proportions of the component parts of the elements which enter into their existence. For instance, a solder in which tin forms a component part will flow or fuse much sooner than one in which copper and silver alone enter into composition, or of one wholly composed of copper, silver, and zinc, or of silver and brass; therefore it must be understood that tin is the best metal for increasing the fusibility of silver solders, and for keeping up their whiteness. Nevertheless it should always be used sparingly, and even then drawbacks will present themselves such as we have already alluded to.

It is our intention to give a list of the various solders which have been usually employed with more or less success, so that the silversmith and the art workman will be enabled to select the one most suitable to the particular branch of his trade; and we contend, from experience in the craft, that success of workmanship mainly depends upon this point.

Hardest silver solder, cost 3_s._ 9_d._ per oz.

oz. dwts. grs. Fine silver 0 16 0 Shot copper 0 4 0 ---------------- 1 0 0 ================

Hardest silver solder, same as above.

oz. dwts. grs. Fine silver 1 0 0 Shot copper 0 5 0 ---------------- 1 5 0 ================

Hard silver solder, cost 3_s._ 6_d._ per oz.

oz. dwts. grs. Fine silver 0 15 0 Brass 0 5 0 ---------------- 1 0 0 ================

Hard silver solder, same as above.

oz. dwts. grs. Fine silver 1 0 0 Brass 0 6 16 ---------------- 1 6 16 ================

Easy silver solder, cost 3_s._ 2_d._ per oz.

oz. dwts. grs. Fine silver 0 13 8 Brass 0 6 16 ------------- 1 0 0 =============

Easy silver solder, same as above.

oz. dwts. grs. Fine silver 1 0 0 Brass 0 10 0 ---------------- 1 10 0 ================

The silver solders here given are not such as we can confidently recommend to the general silversmith, having proved them to be very unsatisfactory in certain classes of work. For example, the first solder, except in the case of plain strong work, would be far too infusible to be generally used by the silversmith; the second, although much more fusible, cannot safely be applied to very fine and delicate wire-work, because the brass in its composition is so uncertain: unless specially prepared by the silversmith, it probably, if purchased from the metal warehouses, contains lead; the latter is injurious, and in process of soldering it burns and eats away, much resembling the application of burnt sawdust to the work. No really effective work can be produced when the above symptoms present themselves. The same remarks apply to No. 3, which is the most fusible, and when free from lead or other base metal it may be classed as a tolerably fair common solder. In the preparation of the solders to which we are alluding, it is preferable to employ, instead of the brass, a composition consisting of a mixture of copper and zinc, in the proportion of two parts of copper to one part of zinc; the operator then knows of what the solder is composed, and if it should turn out bad he will partly know the cause, and be able to supply a remedy.

The solders that we have found to answer our purpose best are composed of the following elements. The first is described again as _hard_ solder, but it is not nearly so hard as the one previously described.

Best hard silver solder, 3_s._ 9_d._ per oz.

oz. dwts. grs. Fine silver 0 16 0 Shot copper 0 3 12 Spelter 0 0 12 ------------- 1 0 0 =============

Best hard silver solder, same as above.

oz. dwts. grs. Fine silver 1 0 0 Shot copper 0 4 9 Spelter 0 0 15 ------------- 1 5 0 =============

Medium silver solder, 3_s._ 6_d._ per oz.

oz. dwts. grs. Fine silver 0 15 0 Shot copper 0 4 0 Spelter 0 1 0 ------------- 1 0 0 =============

Medium silver solder, same as above.

oz. dwts. grs. Fine silver 1 0 0 Shot copper 0 5 8 Spelter 0 1 8 ------------- 1 6 16 =============

Easy silver solder, 3_s._ 3_d._ per oz.

oz. dwts. grs. Fine silver 0 14 0 Shot copper 0 4 12 Spelter 0 1 12 ------------- 1 0 0 =============

Easy silver solder, same as above.

oz. dwts. grs. Fine silver 1 0 0 Shot copper 0 6 12 Spelter 0 2 4 ------------- 1 8 16 =============

Common silver solder, 3_s._ per oz.

oz. dwts. grs. Fine silver 0 12 12 Shot copper 0 6 0 Spelter 0 1 12 ------------- 1 0 0 =============

Common silver solder, same as above.

oz. dwts. grs. Fine silver 1 0 0 Shot copper 0 9 15 Spelter 0 2 9 ------------- 1 12 0 =============

The whole of the above-named solders will bleach or whiten properly if applied to silver of the suitable quality for such purposes. We have used copper and spelter in our silver solders, because we have found from experience that the fewer number of times a solder is melted the better it is for all purposes. This result of our experience is in direct opposition to those authors who have professed to treat upon this subject, and who can have had but a small amount of real practical knowledge, for it is argued by them that the oftener a solder is melted the more properly does it become mixed, and, consequently, the more fit is it for the workman's use. To such arguments we are prepared to give a blank denial, and our reasons for so doing we will state further on in this treatise.

There are various other silver solders used by silversmiths; some few of which it will be as well perhaps, while we are on the point, to enumerate:--

Silver solder for enamelling, cost 3_s._ 9_d._ per oz.

oz. dwts. grs. Fine silver 1 0 0 Shot copper 0 5 0 ------------- 1 5 0 =============

Silver solder for enamelling, cost 3_s._ 2_d._ per oz.

oz. dwts. grs. Fine silver 1 0 0 Shot copper 0 10 0 ------------- 1 10 0 =============

Easy silver solder for filigree work, cost 3_s._ 9_d._ per oz.

oz. dwts. grs. Fine silver 0 16 0 Shot copper 0 0 12 Composition 0 3 12 ------------- 1 0 0 =============

Quick-running silver solder, cost 3_s._ per oz.

oz. dwts. grs. Fine silver 1 0 0 Composition 0 10 0 Pure tin 0 2 0 ------------- 1 12 0 =============

Silver solder for chains, cost 3_s._ per oz.

oz. dwts. grs. Fine silver 1 0 0 Shot copper 0 10 0 Pure spelter 0 2 0 ------------- 1 12 0 =============

Easy solder for chains, cost 3_s._ per oz.

oz. dwts. grs. Fine silver 1 0 0 Composition 0 10 0 Pure spelter 0 2 0 ------------- 1 12 0 =============

Common silver solder, cost 2_s._ 9_d._ per oz.

oz. dwts. grs. Fine silver 1 0 0 Shot copper 0 12 0 Pure spelter 0 3 0 ------------- 1 15 0 =============

Common easy solder, cost 2_s._ 9_d._ per oz.

oz. dwts. grs. Fine silver 1 0 0 Composition 0 12 0 Pure spelter 0 3 0 ------------- 1 15 0 =============

Silver solder with arsenic, cost 3_s._ 9_d._ per oz.

oz. dwts. grs. Fine silver 1 0 0 Shot copper 0 3 0 Yellow Arsenic 0 2 0 ------------- 1 5 0 =============

Silver solder with arsenic, cost 3_s._ 6_d._ per oz.

oz. dwts. grs. Fine silver 1 0 0 Composition 0 6 0 Yellow Arsenic 0 1 0 ------------- 1 7 0 =============

Easy silver solder, cost 3_s._ 2_d._ per oz.

oz. dwts. grs. Fine silver 1 0 0 Composition 0 5 0 Tinsel 0 5 0 ------------- 1 10 0 =============

Common easy solder, cost 2_s._ 9_d._ per oz.

oz. dwts. grs. Fine silver 1 0 0 Tinsel 0 10 0 Arsenic 0 5 0 ------------- 1 15 0 =============

Another common silver solder.

oz. dwts. grs. Fine silver 1 0 0 Composition 0 15 0 Arsenic 0 1 6 ------------- 1 16 6 =============

A very common solder.

oz. dwts. grs. Fine silver 1 0 0 Composition 1 0 0 White arsenic 1 0 0 ------------- 3 0 0 =============

The solders here given will be found amply sufficient to select from, for every operation of the silversmith, and will answer the several purposes for which they have been described. When tin and arsenic are employed in the composition of solder, either together or separately, they should be withheld until the more infusible metals with which they are to be united have become melted; the tin or tinsel should then be added, and when this is well melted with the mass, fling on the top the arsenic, let it melt, stir it well together, and pour it out quickly into an ingot mould already prepared for its reception.

When silver and brass, or silver and composition, alone form the component parts of the solder, these metals may be put into the melting-pot together, well fused, stirred, and poured out as before.

Solders into which volatile metals enter, upon repeated meltings, become hard, brittle, and drossy, and are therefore not so good as when the metal has received only one melting; it is for this reason that we have always preferred to manufacture our solders from metals which have not been melted before, or from those which have gone through the process as few a number of times as possible.

The mode of soldering gold and silver is as follows: Take the solder and roll it out thin between the flattening rollers, or file it into dust, according to the kind of work in hand. If filed into dust, it is all the better if done very fine; and if reduced to a flat state, which should be tolerably thin, cut it into little bits, or pallions, which may easily be performed with a pair of hand-shears, length-ways and afterwards cross-ways. When this is done, take the work which is to be soldered, join it together by means of fine binding-wire (very thin iron wire), or lay it upon the pumice so that the joinings can come close together, and will not be liable to move during the process; wet the joinings with a solution of borax and water, mixed into a thick paste, applying it with a small camel-hair pencil; then lay the bits or pallions of solder upon the parts to be united, and having placed the article upon some suitable object, take your blowing instrument (Fig. 16) and blow with it, through a gas-jet, a keen flame upon the solder in order to melt it; this will render the unification of the parts complete and compact.

When filed solder is used, the process of charging the article is rather different from the above. In the latter case the filings are commonly put into a small cup-shaped vessel (Fig. 17), in most cases the bottom of a tea-cup, or some other similar vessel, being used for the purpose; a lump of borax is then taken and rubbed upon a piece of slate, to which a little water is occasionally added during the rubbing; when this solution attains the consistency of cream, it is put into the solder-dish and well mixed with the solder. This is then applied to the article to be soldered, by means of a charger, consisting of a piece of round metal wire, flattened at one end, and shaped for the purpose it has to serve. The joinings, when this kind is employed, require no boraxing with the pencil, as described under pallion solder; the borax being intermixed with the solder flushes with it through the joinings to be united, thus rendering any further application unnecessary. The process to which we are alluding is called "hard soldering," and cannot be applied to metals of a fusible nature; neither must it be attempted in the case of goods bearing the name of plated, which are put together with soft or pewter solder, similar to that used by tinsmiths and gasfitters. If there should be any soft solder about the article, to be soldered by the means we are describing, it would be almost certain to destroy it, the soft solder having such an affinity for entering into combination with metals more infusible than itself when overheated.

There is an art in soldering greater than some people would believe. The heat required is of various degrees, some articles requiring a broad rough flame, others a smooth one, and others again a fine pointed one. All these circumstances connected with the process, together with others which we could detail, proving that it is an art only to be acquired by practice, must be considered enough; and we proceed to observe that the skilful jeweller in soldering a large piece of work will direct the flame of the gas jet to all parts of it, until it is tolerably hot, and then return to the spot to be soldered, and by a very dexterous movement of the flame, produced by the blow-pipe, increase the heat at that spot until the solder has flushed and the parts are rendered thoroughly secure. So far as some of the work of the silversmith is concerned, the process of soldering is a very delicate operation, and ought not to be undertaken by an unpractised hand.

The method of preparing solder for filigree work is worthy of a passing notice. It is called by the Germans Lemaille solder. In the first place it is reduced to very fine filings, mixed with burnt borax powdered fine, and in this state it is sprinkled from a spouted grater over the work to be soldered. The English filigree workers commonly use clean filed solder, and by means of the camel-hair pencil apply a solution of borax to the work, and then sprinkle the dry solder upon it from the grater.

In Vienna a kind of powdered borax is employed, called _Streu borax_, or sprinkle borax. It is composed of the following ingredients, which should be gently annealed to expel their water of crystallization, the whole well pounded and mixed together, and sprinkled over the parts to be joined from the spouted grater as before:--

oz. dwts. grs. Calcined borax 0 17 12 Carbonate of soda 0 1 12 Common salt 0 1 0 --------------- 1 0 0 ===============

The object of this mixture is to prevent the rising of the solder, and to facilitate its flushing. Too much of it should not, however, be put with solder in the grater at one time, as it is as objectionable as too much borax applied in the ordinary way, but every workman will learn from experience concerning these matters. We have tried this mixture, prepared with filed solder in the ordinary way, and found it advantageous at first; but its greatest drawback is the turning of the solder yellow if not quickly used upon the work after mixing, thus rendering the solder permanently injured. For this reason we have had to abandon its employment in the wet state. But, in its dry state, to the silversmith for filigree purposes it is likely to be of advantage. It may be remarked that this preparation encumbers the work with a great deal more flux than borax does, and consequently it requires to be more often boiled out during the period of soldering together the component parts. This is effected by boiling in a weak pickle of sulphuric acid and water, composed of the following proportions: one part of acid to thirty parts of water.