The Art of Lead Burning / A practical treatise explaining the apparatus and processes.

by C. H. Fay

Do Not Hurry.

The point to be taught here is that you must not attempt to hurry this work or holes will surely be burned in the sheets, which oftentimes makes difficult work to patch. The old adage, “haste makes waste,” can well be applied to lead burning. Sufficient time must be allowed for one drop to set before attempting to place the next drop. Time spent on practicing at the bench is time well spent, as many little details that cannot be brought to the beginner's attention here will be learned in that way and stored in his mind for future application.

CHAPTER IX.
THE DIFFERENT KINDS OF SEAMS.

There are two kinds of seams proper, viz.: The butt seam and the lap seam. The butt seam is used principally for joining horizontal waste pipes and in lengthening traps, or for any purpose where it is desired not to have the point of junction show. This form of seam can be burned clear through—that is, the lead can be heated until fusion takes place nearly through the entire sheet. It is generally necessary to add lead to the seam if it is desired to make the seam as strong as the sheet it joins, unless the article to be burned is of such a size as to be possible to allow of its being burned on both sides, which makes the strongest of seams. The lead for the butt seams is prepared by rasping the edges of the lead sheet to be joined straight and true, Fig. 22, so that when the edges of the lead are brought together they will fit close its entire length. The edges are then shaved for a distance of ⅛ inch each side of the edge, making a seam ¼ inch wide. On stock heavier than 12-pound sheets the edge should be shaved off, making a deep V-shaped groove, and the seams must be made by adding lead. This allows the fusion to take place nearly through the sheet. The butt seam is the simplest form to burn, no matter in what position it is placed.

Fig. 22.—Rasping the Edges of the Lead Sheet Straight and True.

The lap seam is the seam commonly used, and as between the butt seam and the lap seam the latter is generally to be preferred. As it is not necessary to cut and trim the edges true, it dispenses with any additions of lead, except at rare intervals; it leaves the left hand free to handle the shave hook, and the lap can be dressed to fit any uneven spots. It also makes the next best seam to through fusing. By lap seaming a tank can be lined in about half the time required to butt seam the same article, which is an important item to the customer.

Fig. 23.—Burning a Lap Seam.

The lead for this form of seam is prepared, as its name indicates, by lapping one sheet ½ to ¾ inch over the other sheet. The under edges are to be shaved clean, as also the upper edge. The lead required to make the seam is melted from the upper lap and is fused on the lower sheet. There is no reason why the lead at the point of juncture cannot be made as thick as the original lead. This is the point aimed at in practicing, and the only accurate way to determine the relative strength of the seams is to cut squarely across a finished seam, then bend the beam slightly. The thickness can then be noted. A cross section of a perfect lap seam is shown at a in Fig. 23. The beginner should practice the different seams until the thickness of the joint can be told by the looks of the lead. A few days' diligent practice at the bench will soon train the eye to note any imperfection that may arise.

The different seams will be taken up serially. A description of how the seams are prepared and the several positions of the blow pipe, as well as the little difficulties that may arise, is the extent of the instruction that can be given. The rest must come with practice and the application of a little common sense. There is no royal road to this business; but practice, and practice hard, is the only way to satisfactorily master the blow pipe and flame, and in practicing remember that all this work has been done before, and can be easily done again, and by you. Do not get discouraged by failure to make a perfect seam at the first application, but stick to it for a short time and it will be found to be a most fascinating pastime, for which the persistent student will eventually be well repaid.