This process of joining metals is much used by tinners and other sheet-metal workers for joints requiring but moderate strength. It is a simpler and more convenient process then brazing, as solder melts at a low temperature.

A soldering outfit consists of the following-named items: (1) Soldering irons (more correctly called soldering coppers) as shown in Fig. 254. The lower copper is for heavy work.

Fig. 254.   Soldering Coppers.

Fig. 254. - Soldering Coppers.

(2) Heater for soldering irons. This consists either of a small sheet-iron fire pot in which a fire of coke or charcoal is kept, or a gasoline torch with an attached rack for supporting the coppers in reach of the flame.

(3) Lead pans or cups for holding flux and acid to assist in soldering.

Solder, like spelter, varies in the proportions of its constituents according to the degree of hardness required, but the usual composition is 1 part lead and 1 part tin for tinners' work, or 2 parts lead and 1 part tin for plumbers' work. The ingredients of solders and spelters must be pure. Tinners' and plumbers' solder is designated as soft solder to distinguish it from hard solder for brazing.