The Process of Plumbing.
When a roof is to be covered, or a cistern lined, with lead, the sheet of the metal is unrolled on a level floor, and made free from creases and undulations, by beating them down with a heavy wooden flogger, formed like a roller with a flattened side, and a handle to it. The plumber then draws on the lead the form into which it must be cut to fit the surface it is intended to cover, and afterwards cuts through the lines described with a strong sharp knife. The piece is then rolled up again for facility of carriage, and raised by tackle into its intended situation, it being placed there so that when again unrolled, it may lie in the proper situation and position on the boarding. The sheet is then again beat out flat as before.
The next sheet being put into its place, and so that the edges of the two may overlap about one and a half or two inches, the workman proceeds to make the joint, or to solder the two sheets together. The first step for this purpose is to scrape the two edges or borders of the sheets that are to come in contact quite clean and bright, with a tool constructed for this purpose, consisting of a small triangular bit of steel ground sharp at its edges, and fastened at right angles on an iron socket, fixed in a handle. When these borders of the lead are quite clean, they are painted over with black-lead paint, to prevent their tarnishing, or oxidising again, as the solder will only adhere to a clean pure metallic surface. The paint also serves as a flux to cause the solder and lead to melt together, and thus make a close joint.
The solder is melted in an iron ladle, on a rude temporary fire-place, built as near the spot where the solder is wanted as possible. The plumber having turned back the edge of the upper sheet at the joint, an assistant carefully pours the solder on the lower edge. The workman then spreads it evenly along the joint, by means of soldering irons, which are irregularly-shaped iron bars, swelling at their ends into rounded forms of different sizes and shapes, according to the particular purpose for which they are intended. These irons are used in a red-hot state in order to keep the solder melted.
As soon as the workman has spread the solder, he presses and hammers down the upper edge upon the lower, and spreads the solder forced out of the joint, along the seam. The outermost edge of the lead covering is nailed down to the boarding or cistern-frame by nails, with their heads leaded over to prevent the corrosion of the metal, by the chemical or voltaic action that takes place when two metals in contact are exposed to moisture. The situation of the soldered joints depends on the size and form of the surface to be covered over; and a good workman considers well how he can cut out the lead so as to have the fewest joints, and these in the most favourable situations. If he has to line a cistern, he will cover the bottom in one piece, cutting the lead large enough to admit of its turning up for an inch or two at two of the sides, the joint consequently being made at these angles.
When a large roof, like that of a church, is covered with lead, this is laid on in parallel bands as wide as the sheet will admit of, the edge of one sheet being turned over a wooden roller or fillet, nailed down on the boarding to receive it, while the edge of the next sheet is turned over the former lead again; the double thickness being well flogged down to render the joint water-tight: and in this case no solder is used.
The edges of lead gutters that turn up against the inside of the parapet are either laid as flat against the brick-work as possible, and secured so by iron holdfasts, so as to prevent rain from getting in; or to effect the same object, they are in all the better kind of buildings, turned into a joint, in the brick-work, between two courses.
When the plumber has to join two lengths of lead pipe into one, he opens out the end of one length into a funnel-shaped aperture, by gently driving a wooden cone into it, so as to avoid splitting the pipe. The end of the other length is then scraped down a little by the triangular tool before mentioned, not only to obtain a clean surface for soldering, but to allow of the end fitting into the funnel-shaped aperture alluded to. The two pipes being thus put together, the workman holds a thick wadding of old woollen cloth, well greased, under the joint, while a labourer gently pours melted solder over the joint, which the plumber smoothes and shapes down by his soldering-iron and the cloth into a regular smooth rounded swelling, all round the joint, making this perfectly close and water-tight.
We observed in the chapter on “Roofs,” that within the last few years, the metal zinc has been much used instead of lead for all the purposes of the latter, and many others beside, for which the admirable qualities of zinc particularly qualify it. This metal is lighter than lead, and equally durable in the open air. It bears water almost equally well; but it is not so flexible or manageable, being neither so fusible nor malleable. Zinc only admits of being rolled or hammered when it is heated to about two hundred and twenty degrees of Fahrenheit. When cold it is too brittle to bear much bending; nevertheless, pipes, gutters, cisterns, chimney-pots, &c., are made out of sheet zinc; and roofs, &c. covered with it.