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.
Fig. 50.—Pipes Supported and Secured on Bench for Joint Wiping
