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The Practical Mechanic:
Every Man His Own Mechanic
Broken Window, How To Mend It
Knowledge Must Be Paid For
Kinds Of Woods Used In Carpentry
Toosl Used In Carpentry
The Glue Pot
The Carpenter's Bench
How To Hold And Handle Tools
Divisions Of The Building Trade
Soldering And Brazing
Indoor And Outdoor Painting
Varnishes And Recipers For Making Varnishes
Polishing And Recipes For Polish
Wall Paper Hanging
( Originally Published 1902 )
For zinc-working, plumbing, gasfitting, and all kinds of work in sheet metal, a knowledge of the processes termed soldering and brazing is necessary. By these processes the edges of pieces of sheet metal are joined together, and although it is better for the amateur, for safety's sake, to have all zinc-working that he may require in the way of covering roofs, making zinc pipes, lining wooden cisterns, and similar operations, done by the professional zincworker, and to call in the plumber and gasfitter to rectify any leakage in lead pipes or gasfittings, it is as well that he should know how to make a joint in metal, whether sheet or pipe, and possess the few appliances necessary for doing so. If he can do no more than repair tin pots, kettles, etc., it will be of advantage to him, for the itinerant tinman seldom does his work effectually, and seems never to be at hand when his services are most required.
First, then, with regard to soldering and brazing. They may both be described as methods of uniting pieces of either the same or different kinds of metal with a strong and, if necessary, water-tight joint. To effect this by the first-named operation, namely soldering, a compound metal called solder is used. This composition is melted, but the metals to be united do not require to be heated otherwise than through contact with the melted solder.
In the operation of brazing the metals to be joined must be raised to the melting point of the brazing composition, which is soft brass. Although this makes the strongest joint, the necessity for exposing the articles to such a great heat renders this operation inapplicable to many purposes.
Soldering is very useful for joining copper and copper, copper and brass, copper and iron, brass and brass, brass and iron, tin and tin, and tin and any other metal. If the joint has to stand a rather high degree of heat-such, for instance, as the seams of a small copper steam boiler-a hard solder must be used. By hard solder is meant one that only fuses at a high temperature; a soft solder, on the contrary, fuses at a low degree of heat.
How Soldering is Done.
The surfaces to be united must be thoroughly cleaned and brightened. Without this the metal will not adhere. The soldering iron must be warmed sufficiently to melt the solder; it must not be made red-hot, because the solder will not "hold to it."
Whilst the iron is warming, tin the surfaces by brushing them over with muriatic acid, dipping them into melted solder, and quickly rubbing off the adherent metal. This, if done well, will leave a thin coat of solder. When it cannot be done thus, the surfaces must be tinned by means of the soldering iron. In this case they must be coated or washed with the acid as before, but the solder must be melted on the places required with the hot iron.
When tinned, the surfaces should be brought close together, a little acid rubbed along the joints, and the iron dipped in the acid and put against some solder, so that the melted solder will stick to the iron. The iron must now be applied to the joints, and drawn slowly along in such a manner that the metal between the joints is melted, and the joints filled up. A little practice will soon make the amateur tolerably skilful in doing this. The muriatic acid, or spirit of salt, as it is sometimes called, must be killed, or rendered neutral, before it is used, and this is done by putting one or two small pieces of zinc into it and allowing it to expend all its energy on this. Killed acid is much more effective than the raw or pure acid. . Sometimes resin is used instead of the acid; but the neutralized acid is preferable, because it does not leave the work in such a mess as resin.
Should it be desirable for the solder not to adhere to any portion of the article, a paste must be made with whiting and water, and put about those places; this paste will harden with the heat, but can be removed after the soldering operation is effected.