The Flux.
—Borax is the best-known flux for brazing. It is beneficial, however, to have the borax calcined (fused), as it settles down to its work immediately when applied to the hot metal, whereas uncalcined borax has a tendency to swell and fall off the work.
Spelter is in the form of filings, a thin stick, or wire. Filings are apt to be blown from the work. Brazing is a very useful, and, if properly done, reliable, method of joining two pieces of iron. A brazed joint is considerably stronger than a soft-soldered one, and easily resists temperatures that would cause ordinary solder to run.
The process is not at all difficult if there is sufficient heat, and, for those who have no gas laid on, the purchase of a paraffin Ætna brazing lamp can be recommended. With this lamp, of course, the bellows is not used, and only an iron hearth with asbestos cubes is wanted; but gas should be used if available.