Plumbers’ Solder.

—As already stated, coarse, or plumbers’ wiping solder, is made in the proportion of 2 of lead to 1 of block tin. Care must be taken that the lead is quite pure and free from any other metal, as zinc-adulterated solder will be difficult to use, and joints made with it on service pipes will not be sound. In melting up scrap lead for making solder, only sheet lead should be used, as the lead used in the manufacture of sheets is much purer and contains a greater proportion of pure pig lead. The scraps must be quite dry; a damp piece dropped into a pot of molten metal may cause a serious accident, as the contents of the pot may be blown out.

To test the quality of solder when made, heat it as for wiping a joint; the correct temperature is determined by dropping a small piece of newspaper into the pot, and if it quickly burns and catches alight the solder is right for using. Next pour a small quantity on to a cold but dry stone or cement floor. This, on cooling, should have a few spots on the surface about the size of a threepenny-piece, and on the under side should be bright nearly all over. Solder of this quality would, if properly used, stand any pressure without sweating. If the solder on the stone or cement floor looks white on both sides, or has a few small bright spots on the under side only, it is too coarse and requires more tin. On no account should the solder be heated to redness, as the tin rises to the top and quickly turns to dross (see p. 11). If this should happen to solder that is being used for service pipes, it should be rectified by adding more tin.

To purify a pot of “poisoned” solder (solder that contains zinc), melt, stir in a handful of common sulphur or powdered brimstone until the mass is of the constituency of wet sand, heat to the ordinary working temperature, and carefully remove the crust that forms on the top, and the solder will then be fit for use, except that a little tin must be added to it. The presence of zinc in solder can be detected by the difficulty of forming joints, the metal falling apart and working very lumpy, and the joints when finished having a dirty grey appearance.

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.

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.

The Cloths.

—Solder cloths for underhand joints should be from ¹/₂ in. to ⁷/₈ in. wider than the joint for which they are to be used, and about ¹/₂ in. longer than they are wide. Most plumbers use the same cloths for underhand and upright, but it is preferable to use a special cloth for 4-in. upright joints with the length 1 in. less than the width. For getting up the heat of an underhand joint on a small pipe a larger cloth may be used until the worker is sufficiently skilled in joint wiping not to burn his fingers when using the correct size. For 3-in. joints and upwards a large cloth must be used first to get up the heat, the wiping cloth being kept warmed and ready for use when the heat is right. This large cloth, as used by some plumbers, is often long enough to lay on the worker’s arm, but this is clumsy to use when the joint to be wiped is in a cramped position, and is liable to let the pipe get burnt, as the metal it holds cannot be readily distributed round the joint; 8 in. by 9 in. is a good size to practise with on the bench, and as more skill is obtained it can be reduced to 7 in. by 7 in. A diagonal strap should be stitched to the back to take the little finger and thumb; the position for this can be obtained by laying the cloth face downwards and placing the hand on it with the finger slightly spread; the wrist should be over the right-hand corner, so that when the cloth is being used the edge is readily kept parallel with the sides of the pipe. Branch cloths are made from 1¹/₂ in. to 2¹/₂ in. wide and about half as long again in width. These cloths should be about seven thicknesses of material, all others being nine or ten.

White moleskin cloth is obtained from the tailor’s for making these solder cloths, is usually 1 yd. wide, and costs about 3s. per square yard. The usual method of making cloths is to cut a strip down the selvedge of the material and fold up the strip till the desired size is obtained; it can then be cut off the piece, and any odd ends left may be used for packing a larger cloth. Another method is to cut a square piece the required size, and then fold it three times each way. This makes a rather clumsy cloth for small sizes, but makes a very good “blanket.”

Horizontal or Underhand Joints.

—For making a successful wiped joint, the ends to be joined must be a good fit and the temporary fixing must be sufficiently strong so that the joints will not be broken in the process of wiping. These two points should be always strictly attended to. Service pipes should be tightly pressed home one in the other, the cupped or female end shaved inside with a knife, but not close in as is the case with soil or waste pipe; this allows the solder to fill up the cavity, which effectually prevents any tendency to sweat. This principle is followed up by some plumbers with branch joints on small size service pipes, the male end being worked in with a twisting motion, to prevent any solder getting into the pipes. All other pipe joints should be closed, the female end being tightly worked in round the male end of pipes as an extra precaution against the solder getting inside. It is a good plan to black the inside of waste and soil pipes, so that the solder will not adhere if any should get through when making the joint. Fig. 50 shows the wiping of an underhand joint.

Beginners often spend a lot of time practising “rolling” underhand joints. This is bad practice, and will be of no use in wiping fixed joints. Little advice can be offered with regard to the actual wiping, constant practice being the essential thing. See that the solder is at the correct heat. This is readily found by dropping a piece of newspaper into the pot, and, if it quickly browns, the solder is ready for use. If the solder is used too hot it will quickly burn holes in the pipe, and if not hot enough a heat cannot be properly worked up, and the cloth may get torn trying to move hard metal. For underhand joints pour on steadily with a circular motion on to the sides of the joint, and on to the soil at the ends of the joint, until sufficient solder in a molten condition can be brought up to cover the top of the joint with the cloth, which is held underneath it; then pour steadily all over the solder until it runs back again. Repeat this continuously until the solder can be worked in a substantial body all round the joint without any hard solder being left at the underneath edges. Give the joint a last pour on, and wash all the solder into the cloth. Bring the solder smartly on to the top, and quickly work it all round the joint with the wiping cloth, using two fingers of one hand for the top and back edges, and the index fingers of both hands for the underneath part. The top of the joint should be roughly shaped first and the surplus metal brought over the back to the underneath; this should be worked into the bottom of the joint with a slight sideways motion. The extra body of metal should be used to warm up any hard edges, the surplus being brought up again to the top and quickly thrown off to the back.

Upright Joints.

—These are more trying to the worker’s patience but are the easier to wipe. After the pipe has been fixed in position, a lead collar should be fixed a few inches below the joint to catch the surplus metal. A piece of stout string tied by a half hitch round the pipe will prevent any leakage of the solder. In working up the heat of an upright joint, care should be taken to work steadily round the joint so that the heat is the same throughout. After sufficient metal has been splashed on with the splash stick and ladle, and the metal is at a moving heat, roughly shape up the joint with the splash stick, keeping the metal fairly high on the joint; then splash on a little more hot metal all round. A warm cloth is now used to shape up the joint by bringing the lower metal up to the higher part, after which start to wipe first with the hand as far round the back of the joint as possible and bring the surplus metal to the front, the cloth being held by the thumb and the index and little fingers; then change the cloth to the left hand and repeat the operation. The joint should be finished off at the back, although if quickly done the finish off should not be apparent. The collar must now be taken off and the solder it contains melted with a plumber’s iron.

A plumber’s iron can be used to good purpose on these joints, especially if they are out of doors and the weather is rough. The iron must be heated to redness and well filed up.

Where possible, all joints to be wiped in their permanent position are sprung away from the wall and temporarily fixed with steel points made from ¹/₂-in. hexagon steel about 9 in. long and drawn out to a point at one end. In some cases, more particularly soil-pipe work, the pipes cannot be fixed away from the wall; a hole must then be cut into the wall about 4 in. back and about 12 in. square to allow the joint to be properly made at the back.

Wiped Joint between Lead and Cast-iron Pipes.

—In wiping a lead pipe to a cast-iron pipe perhaps the best practice is to file clean the end of the cast-iron pipe first and then coat with pure tin, sal-ammoniac being used as a flux. The pipe then is washed to remove the sal-ammoniac, and afterwards “retinned,” using resin and grease as a flux. A plumber’s joint then is wiped in the usual way. It is necessary to take great pains to make a good sound strong joint between the two metals, but even then in the course of time (it may be only a few years) the iron will come out of the solder. The first sign of decay will be a red ring of iron rust showing at the end of the joint. This rust will swell a little and cause the end of the soldering to slightly curl outwards. Eventually the rust will creep between the solder and the iron and destroy the adhesion of the one to the other. The joint would eventually become a loose ring on the iron pipe, but not on the lead pipe, as the expansion of lead and solder do not differ to any great extent. Only those metals that alloy together can be satisfactorily joined by soft soldering, and the solder should contain as great a proportion as possible of the metals to be united.

The illustrations to this chapter (Figs. 46 to 55) are self-explanatory.