_First_, in a cast-iron pot melt the lead to about 800, or a dull red.
_Second_, clean off the dross.
_Third_, add (to a 15-pound pot) 1/2 pound of sulphur in three applications. Each time mix the sulphur thoroughly with the metal with a long stick.
_Fourth_, add tin before the last application of sulphur. Mix thoroughly.
_Fifth_, pour off two bars and look for the frosty streak in the center. Add a little more tin, if necessary.
TO MIX WIPING SOLDER.--
_First_, proceed as described in 1/2 and 1/2, melting the metals and _burning_ out with sulphur, adding the percentage of tin according to the preceding table. Then test the solder for bright spots on the under side.
_Second_, keep the metal thoroughly mixed when burning and keep all dross cleaned off the surface.
The working heat of wiping solder is 500F. Sulphur is used to collect all zinc and dross. The sulphur should come in contact with all parts of the metal. This is why the metal should be stirred when the sulphur is put in.
A few good points in the economical care of solder are listed below.
CARE OF 1/2 AND 1/2 SOLDER.--
_First_, do not drop melted solder on the floor or dirty bench.
_Second_, use all small ends by melting on a new bar.
_Third_, put clean paper under work and use droppings.
_Fourth_, have the mold free from dirt when pouring.
CARE OF WIPING SOLDER.--
_First_, do not heat red hot.
_Second_, do not file bra.s.s where the filings will get into the solder.
_Third_, do not allow lead chips to get into the solder.
_Fourth_, clean the solder occasionally.
_Fifth_, learn to distinguish solder from lead by its hardness.
_Sixth_, have different-shaped pot for lead and solder.
_Seventh_, do not _tin_ bra.s.s by dipping into solder.
_Eighth_, do not put cold or wet ladle into hot solder.
A pot holding about 15 pounds of solder is the size commonly in use.
CHAPTER IV
MAKING AND CARE OF WIPING CLOTHS
A good wiping cloth is essential for wiping joints. The exact size and the flexibility of the cloth depend a great deal upon the mechanic who handles the cloth. Some mechanics like a stiff cloth, but the writer has always used a flexible cloth. The sizes, shape, and methods of folding and breaking in as shown in Fig. 21 below have proved successful. Cloths made of whalebone ticking are inexpensive and make the best for ordinary use.
[Ill.u.s.tration: FIG. 21.--Folding a wiping cloth.]
Size of cloth open Size of cloth folded 14-1/2 by 14-1/2 inches equals 3-1/4 by 3-1/4 inches 13-1/2 by 13-1/2 inches equals 3 by 3 inches 8-1/2 by 12-1/2 inches equals 2 by 3 inches
For the joint-wiping jobs to follow, the above sizes are the best.
The largest size, 14-1/2 by 14-1/2 inches is used for _catch cloth_. The 13-1/2 by 13-1/2 inches is the _wiping cloth_. The 8-1/2 by 12-1/2 inches is the _branch cloth_.
Proceed as follows to cut and complete a cloth:
_First_, lay the ticking on the flat bench and square the sides 14-1/2 by 14-1/2 inches.
_Second_, the ticking should be cut off with shears and not torn or cut with a knife.
_Third_, fold as shown in the cut.
Each fold should be moistened with a little water and pressed with a hot iron. The cloth should not be pulled or stretched, but should be kept as square as possible.
The first and second folds require a little care; the corners when folded to the center should be kept in a little, thus making the outside edge slightly rounded. If this is done, the corners will not stick out when the cloth is finished. After the cloth is carefully folded, pressed, and dried, take a needle and thread and sew the open corners about 1/2 inch in from the edge of the cloth.
By carefully studying the cut, one can readily see each operation and, by following directions, make a perfect cloth.
When the cloth is done, an amount of oil sufficient to soak through about three layers of cloth should be applied and then rubbed on a smooth surface. The oil should be rubbed in well about the edges.
It will not be necessary to apply anything else to the cloth to prepare it for wiping. Paste, soil, chalk, etc., are not needed and do not benefit the cloth. When using oil on the cloth, it must not be used too freely, that is, the cloth must not be soaked in oil, as oil is a rapid conductor of heat and the cloth would soon become too hot to handle.
CARE OF WIPING CLOTHS.--The ticking will burn if allowed to become too hot. If hot solder is poured directly on the cloth, it will soon burn and be destroyed.
Keep the surface on both sides of the cloth well oiled.
Use both sides of the cloth.
Use both wiping edges of the cloth.
[Ill.u.s.tration: FIG. 22.--Wiping cloth folded has 16 thicknesses of ticking.]
When the cloth is not in use, it should not be thrown in with the other tools and allowed to curl up into all sorts of shapes, but should be kept in some flat place. A good way to keep the cloths is to have two pieces of wood between which the cloths may be kept and held there by means of a strap. The length of time which a wiping cloth can be used depends a great deal upon its making and upon the care which is given it.
CHAPTER V