2. Borax slate: a square piece of slate with a small depression in one side. Any piece of clean slate will do. This is used to grind the lump borax, or to mix the pulverized borax to a pasty condition on.
3. Solder: silver solder, sometimes called hard solder. It can be bought by the sheet in large or small quantities. Bunsen burner, or either one of the following: blowpipe and foot bellows with gas flame, a blacksmiths' fire with coke or charcoal.
Directions: The parts of the metals to be joined should, first of all, be scraped or filed bright. This prepares them best for the solder. Take a lump of borax, grind it up and mix with a little water, on the slate, until it is like a paste. Take a sheet of silver solder, cut a number of slits lengthwise down the sheet and then cut them crosswise. You will have a number of pieces about 1⁄16 in. square. These bits are dropped into the borax solution until they are completely covered with the paste. With a camels' hair brush, wash the edges of the metal to be joined, with the solution of the borax. Tie the pieces together with an iron binding wire, taking care to have the edges to be joined close together and in the proper position. If you don't, the solder will not fill up all the openings and cracks, and parts will be left unsoldered. Now, wash all around the joint with the borax solution. Place bits of solder at intervals along the joint, fairly close. Warm the work gently in the flame. This drives off the water in the borax solution. When the borax is quite dry in the joint direct a stronger flame over the whole work. Heat it gradually, but be careful that no part of the metal, except that around the joint, becomes red-hot, and that both sides of the joint get red-hot at the same time. If you don't guard this, the solder will climb to the hotter side and leave the other, and the edges will not unite. Cool it off in water and file the joint perfectly smooth.
SOFT SOLDERING
For mending teakettles, tin cans, tin cups, or anything made of tin, galvanized iron, or lead.
Material: Lead solder, comes in small bars. Flux (1.) Resin and sweet oil. (2.) Muriatic acid. (3.) Tallow candle.
Tool: Soldering iron (can be made out of a piece of half-inch round copper.)
How to solder: Soft solder is a mixture of tin and lead in even proportions. This solder melts at a very low temperature. That is why we can do the work with the soldering iron. I find I can solder many things at home with the soft solder, and I'm going to tell you how I mended a leak in the teakettle the other day. First, I took a pocket knife and cleaned all around the hole or leak, scraping the dirt off both inside and out. Then I mashed a little resin up fine and mixed a little sweet oil with it. Then I washed inside and outside of this leak with the mixture. After heating my soldering iron in a stove (any kind of fire will do) I took a bar of solder, held it over the leak, and melted off a bit with the hot iron. You can make the solder flow over the leak by pressing the iron right on the hole. You see, the heat of the iron melts the solder and at the same time it heats the tin hot enough to make the solder cling to it. Before the part got cold I rubbed off the oil and resin with a woollen cloth. This left the work nicely cleaned. You can mend any leak in anything made of tin, in this way.
Galvanized iron utensils are soldered in exactly the same way, but you must use muriatic acid in place of the resin and sweet oil. But if you wish to solder anything made of lead or pewter a tallow candle is rubbed over the place to be mended, instead of resin and sweet oil or muriatic acid. In every other way the work is just the same. But lead, you know, melts at a very low temperature, so you must be careful when working on it that your soldering iron is just hot enough to melt the solder and not hot enough to melt the lead. And now I am going to tell you how you can make your own soldering iron out of copper.