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
Another recipe is to place in the pot 1⁄4 lb. of size or diluted molten glue and a little water; gently warm until the size dissolves, but do not boil. Mix 1⁄2 cub. in. of chalk ground to a fine powder with a pennyworth of lampblack, and then with a pallet knife incorporate some of the melted size with the mixture on a flat board or stone to form a thin paste, after which place the whole in the pot, warm, and stir together thoroughly. Test as before. Old and thick soil is thinned with porter or stout, but do not add too much or the soil will become so sticky that the solder will cling to it. A little brown sugar, or a little stout, added to the black will make it more tenacious, and cause it to dry with a slightly glossy surface. Some plumbers soil their joints after they are made, with black japan or thinned Brunswick black. But it is doubtful whether the effect is so good as when a “dead” black, such as given by ordinary soil, is used.