When plumbers’ solder is bought ready for use from the manufacturers, it is usually in the form of casts of eight bars, weighing about 56 lb. to the cast. The best only should be used, as cheap solder is frequently the cause of much trouble if used on high-pressure work, and joints made with it are never of good appearance. To test manufacturers’ solder, wipe a joint with it, and if it is of good quality it will work easily at a good heat, and when cleaned off with tallow and a clean rag it should be well covered with bright spots.
Brass fittings should not be tinned by dipping into the solder pot, as brass being an alloy of zinc and copper, the zinc may be melted into the pot with disastrous results.
Flux.
—The flux used is tallow, no other flux answering the purpose so well, although mutton fat has been used as a substitute. Plumbers often call tallow “touch,” and they frequently use it in the form of tallow candles, the cotton wicks coming in handy for packing spindles of taps and slides of gas pendants.
An excellent plumbers’ black, soil or smudge, can be bought in packets, and requires only to be mixed with water before using. Ordinary black consists of lampblack, glue, and water. The black should be first mixed with water, afterwards adding the glue, which must have been previously melted in a glue-pot. Simmer this for a time to remove surplus water. Test the black on a piece of sheet lead and dry off slowly. If it chips, add more black, but if it rubs off add glue.
The black should be made in small quantities, as it deteriorates if kept.
Fig. 48.—Joints prepared for Jointing
Fig. 49.—Marking-gauge for use on Pipe Ends