Successful soldering will present no serious difficulties to anyone who will follow a few simple directions. Certain metals are easier to join with solder than others and some cannot be soldered at all. Copper, brass, zinc, tin, lead, galvanized iron, gold and silver or any combination of these metals can be easily soldered, while iron and aluminum are common metals that cannot be soldered.
It is necessary to possess a soldering copper, a piece of solder, tinner's acid, sandpaper or steel wool, a small file and a piece of sal ammoniac. If the soldering copper is an old one, or has become corroded, it must be ground or filed to a point. Heat it until hot (not red hot), melt a little solder on the sal ammoniac, and rub the point of the copper on it, turning the copper over to thoroughly tin the point on each face. This process is known as tinning the iron and is very necessary to successful work.
After the copper is tinned you may place it in the fire again, being careful about the heat, as too hot an iron will burn off the tinning.
The parts to be soldered must be thoroughly cleaned by sandpapering or the use of steel wool until the metal shows up bright. Then apply the acid only to the parts to be soldered with a small stiff brush or a small piece of cloth fastened to a stick, or in a bent piece of tin to form a swab.
Tinner's acid is made by putting as much zinc in commercial muriatic acid as will dissolve. This process is best accomplished in an open earthenware dish. After the acid has ceased to boil and becomes cool it may be poured into a wide-mouthed bottle which has a good top or stopper, and labeled "Poison."
Place the parts to be soldered in their correct position and apply the hot copper to the solder, then to the joint to be soldered, following around with the copper and applying solder as is necessary. In joining large pieces it is best to "stick" together in several places to hold the work before trying to get all around them. A little practice will soon teach the requisite amount of solder and the smoothness required for a good job.
In soldering galvanized iron, the pure muriatic acid should be used, particularly so when the iron has once been used. --C. G. S., Eureka Springs, Ark.
Take a cotter pin and bend it over a small rod to bring the points together, as shown in the sketch. This will make a spring clamp that is opened to slip over the articles to be clamped together by inserting a scratch awl or scriber between the legs at the bowed portion. To make a more positive clamp before bending the legs to a bow, slip a short coil of wire over the pin, passing it down to the ring end. Wire 1/32 in. in diameter wound over a wire slightly larger in diameter than that of the cotter will do. In soldering, smoke the legs well to avoid solder adhering to . The clamp is tightened by pushing up the coil ring toward the bow of the legs and then twisting it like a nut, the coil being wound right-handed, so that it will have a screw effect.
Occasionally one finds a piece of soldering to do which is impossible to reach with even the smallest of the ordinary soldering irons or coppers. If a length of copper wire as large as the job will permit and sufficiently long to admit being bent at one end to form a rough handle, and filed or dressed to a point on the other, is heated and tinned exactly as a regular copper should be, the work will cause no trouble on account of inaccessibility. Contributed by E. G. Smith, Eureka Springs, Ark.
The addition of cadmium to soft solder composed of tin and lead, lowers its melting point and increases its strength.