Requisites for Silver-soldering.
—For light jobs in silver-soldering the special tools and materials required are as follow: Suitable gas jet or other flame, mouth blowpipe, scraper, jar containing a sulphuric acid “pickle,” piece of slate, camel-hair brush, pieces of lump borax, two grades of silver solder, charcoal block, iron binding wire.
The pickle is made by pouring 1 part of common sulphuric acid into 20 parts of water, and its function is to remove all dirt and borax from the metal. Silver-soldered articles should not be thrown into the pickle until they are nearly cold, as otherwise the joints may crack, but in the preparatory annealing (that is, softening) of plain metal, wire, rod or tubing, the article may be put into the pickle when hot—but take care of the splashes! Plunging hot copper or brass into cold water does not have the effect of hardening it. Before placing a job in the pickle, remove any iron binding, as this is immediately attacked by the acid.
Often it is advisable to heat the metal and put it “through the pickle” before working on it, especially in the case of tubing that has been lying by for some time and has become dirty.
For heavier work, a foot-bellows and gas blowpipe, or else a blowlamp, are essential. An “Ætna” paraffin blowlamp with horizontal burner will be found quite satisfactory, although, of course, if a gas supply is available in the workshop the user will find that a foot-bellows and blowpipe are more convenient. A blowlamp or blowpipe requires a suitable tray or “forge” of sheet-iron in which coke and odd pieces of brick or tile may be laid and used to pack round the object whilst the flame is being played on the part to be soldered.
Figs. 56 and 57.—Clip for Holding and
Applying Silver Solder
Fig. 58.—Pricker and Spatula for Consolidating Joints and Applying Solder
Among the smaller additional tools that will be required will be a clip to hold the solder ([Figs. 56] and [57]) and a brass pricker ([Fig. 58]).