3479. Soft Soldering

3479.    Soft Soldering. The solder is an alloy of 2 parts tin to 1 part lead, fusible at 340o Fahr.; or, for cheapness, the proportion is sometimes 3 to 2, fusible at 334°. This substance is applied with a hot copper tool called a soldering-iron, or by blowpipe flame. Heat, however, causes the edges of the metal to oxidize; therefore the edges are covered with a substance having a strong attraction for oxygen, and disposing the metal to unite to the solder at a low temperature. Such substances are called fluxes, and are chiefly borax, resin, sal-ammoniac, muriate of zinc, Venice turpentine, tallow, or oil.

3480. Flux for Soldering Brass

3480.    Flux for Soldering Brass. For brass or other similar alloy, resin, sal-ammoniac, and muriate of zinc are the proper fluxes. Should the work be heavy and thick, the soldering requires to be done over a charcoal fire in order to keep the tool heated within proper limits. It is as well to tin the surfaces before soldering; in some cases simply dipping into a pot of melted solder effects the purpose, but the dip must be done instantly to be effective.

3481. Flux for Soldering Zinc

3481.    Flux for Soldering Zinc. Zinc is difficult to solder, from the fact that it is apt to withdraw the tin from the soldering bolt, zinc and copper having a stronger affinity for each other than tin and copper. The proper flux is muriate of zinc, made by dissolving small bits of zinc or zinc drops in muriatic acid mixed with an equal bulk of water.

3482. Flux for Soldering Tin and Lead

3482.    Flux for Soldering Tin and Lead. Tin and lead require resin or oil as the flux.

3483. Flux for Soldering Pewter

3483.      Flux for Soldering Pewter. Pewter requires a flux of oil, and may, in addition to the soldering-iron process, bo soldered by a current of heated air.

3484. Flux for Soldering Britannia Metal

3484.    Flux for Soldering Britannia Metal. Britannia metal should nave muriate of zinc for a flux, and be soldered by the blowpipe.

3485. To Solder Iron

3485.   To Solder Iron. Iron requires the surfaces to be tinned over before being soldered; the method is given in No. 3515.

3486. To Soft Solder Small Articles

3486.    To Soft Solder Small Articles. Join together the parts to be soldered, first moistening them with soldering fluid (see No. 3473 (To Make Soldering Fluid for Soft Solder)), lay a small piece of solder over the joint and apply heat, either over a spirit flame, or by means of the blowpipe, as the case may be. The heat should be withdrawn at the moment of fusion, otherwise the solder may become brittle.

3487. To Soft Solder Smooth Surfaces

3487.    To Soft Solder Smooth Surfaces. Where two smooth surfaces are to be joined, moisten the surfaces with soldering fluid (see No. 3473 (To Make Soldering Fluid for Soft Solder)), and lay a piece of tin foil between them, press them together closely, and apply heat sufficient to fuse the tin foil.