zinc chloride
Solder wire is very handy for small work, and can be made in the following way: Roll a sheet of stiff writing or drawing paper into a conical form, rather broad in comparison with its length; make a ring of stiff wire to hold it in, attaching a suitable handle to the ring. The point of the cone should first of all be cut off to leave an orifice of the size required. It should then be filled with molten solder, and held above a pail of cold water, and the stream of solder flowing from the cone will solidify as it runs and form the wire. If held a little higher, so that the stream of solder breaks into drops before striking the water, it will form handy elongated “tears” of metal; when it is held still higher, each drop forms a thin concave cup or shell, and each of these forms will be found to have its own peculiar uses in blowpipe work.
The method adopted for granulating tinman’s solder, which is very rarely called for, is as follows: Place a piece of wood, well greased, over a tub containing water, and by gently pouring the molten alloy from a distance in a small stream on to the greased board, the metal is broken up into a large number of very fine shots, which run off the board into the water and are immediately cooled. The fine shots are then taken from the water and gently dried.
Making Solder from Pewter.
—This alloy is composed of variable proportions of tin and lead, the average composition being about 4 parts of lead to 1 part of tin. If old pewter is to be utilised for making solder, tin will have to be added to the molten pewter. Thus, to convert 5 lb. of average pewter to “coarse” or “common” solder, add 1 lb. of tin; to “fine” or “medium,” add 3 lb. of tin; and to “very fine” or “best,” add 7 lb. of tin. The respective proportions of lead and tin will then be 2 and 1; 1 and 1; and 1 and 2. After the proper quantity of tin has been added, mix some powdered sal-ammoniac with the molten metals, and well stir the alloy; it is then ready for pouring into the moulds.
Making Coarse Solder from Composition Piping.
—Good composition piping is made of nearly all tin, or an alloy of tin and lead, in which the former metal is in excess, and formerly was much used by plumbers in the making of coarse solder, as the material consisted of odd pieces of small value. As, however, a great deal of composition tubing is made out of old metals of which lead, tin, antimony, arsenic, and zinc form the alloy, it is not advisable to introduce it into solder. Should it be done, the melting point of the solder would be raised, and in applying it to the lead to be joined together, would probably partly melt it. Neither do the metals named alloy in a thorough manner, but partake more of the nature of a mixture in which the constituents partly separate when making the joints, and some, especially zinc, show as small bright lumps on the surface. Joints wiped with what is usually called “poisoned metal” are difficult to make, almost invariably leak when on water service pipes, and are dirty grey, instead of bright and clean. The zinc could be removed from the mixture by the method already given.
Combined Solder and Flux.
—This consisted of equal parts of lead and tin made into fine tubing and afterwards filled with flux having resin as a base. “Tinol” is a paste made of finely powdered solder and a special flux, and there is also “Tinol wire” having a core of flux.
A “magic” solder, sold by hawkers, consists of the above tubular flux-filled solder of such low melting point that it can be fused in the flame of a lighted match.
Soft Solders that Melt in Boiling Water.
—The following soft solders melt at a temperature lower than that of boiling water: 1 part tin, 1 part lead, and 2 parts bismuth, melting point about 200° F.; 8 parts lead, 4 parts tin, 15 parts bismuth, and 3 parts cadmium, melting point 140° to 150° F.; 6 parts lead, 7 parts bismuth, and 1 part cadmium, melting point about 180° F. To ensure the alloys melting at the temperatures stated, the metals of which they are formed should be free from impurities, and care should be taken to prevent oxidation while making the alloys. When melting the metals, that having the highest melting point should be melted first, with a layer of resin over it, the other metals being added in the order of their melting points. The alloy should then be well stirred with a wooden stick, and poured quickly into moulds.
Re-melting and Overheating Solder.
—After solder has been re-melted a number of times or has been overheated, its content of tin will be reduced, and the solder will become poorer and coarser. The tin melts earlier than the lead and, being the lighter of the two, floats over it, and is thus fully exposed to the air, the oxidising effect of which on heated, molten metal is extremely active. The oxidised tin forms a dross, from which most of the tin may, however, be recovered by melting it with powdered charcoal, which combines with the oxygen and frees the tin. The addition of a little fresh tin is desirable.
CHAPTER III
Fluxes Used in Soft-soldering
Why a Flux is Required.
—The great essential to successful soldering is the chemical cleanliness of the surfaces to be united, and the proper use of a flux. Although work may be filed or scraped perfectly bright and clean, this is not the kind of cleanliness which is alone sufficient; there is always in course of formation a film of oxide present, and the duty of the flux is to dissolve this and keep any more from forming. Then, and not until then, will the molten solder “run” and spread over faces in the intimate contact necessary. If this vital precaution of cleaning and fluxing is always observed, the difficulties which many beginners experience in effective soldering will vanish.
Variety of Fluxes.
—There
