The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California
First Aid For The Ailing Houses
The proper method is to heat the metal surfaces to be joined until the solder will melt when it hits them. This will insure a strong and firm bond. Since heat rises, the best method is to use the soldering iron from the bottom, so the heat will rise through the metal and from there into the solder. A large enough iron should be used to make sure the heat is sufficient to melt the solder when it is brought into contact with the fluxed surfaces. If a torch-heated iron is used, two should be on hand—one for the work and one heating.
After the solder has flowed between the surfaces of the metal to be joined (this is called "sweating"), a bead of solder may be made along the exposed edges to provide extra strength. For this, the iron is used above the work. It is kept in firm contact with the metal in order to keep it hot, but the solder is flowed off the tip onto the metal and the previous solder that has been sweated on. This will provide a grip for the bead and will add extra strength to the joint.
Cast iron should not be soldered under normal circumstances. Instead, it should be brazed by a competent professional with the proper equipment. Aluminum requires both a special flux and a special solder, and is generally so difficult to get a satisfactory job that the average home owner may well hesitate to tackle it. The aluminum must be sanded or filed clean, and the powdered aluminum flux promptly sprinkled on it to prevent the corrosion that immediately takes place, dulling the metal. Then the iron heats the aluminum and the special solder is flowed on from the tin to the metal below. Because of its heat conductivity, aluminum should be soldered with a heavy iron, at least 200 watts or 3 pounds. Plastic aluminum is very effective in mending aluminum; heating is not required.
Brass and bronze may be easily soldered with standard flux and solder, but the acid or zinc chloride flux must be removed afterwards with a mild detergent and sal soda solution, or corrosion will take place.
Galvanized iron should be thoroughly cleaned and should then be treated with an acid soldering flux. Ordinary solder may be used. The galvanized area around the joint will be darkened and discolored by the acid, however. Straight hydrochloric acid works the best, but removes the zinc coating around the joint, which may permit rust to start.
Stainless steel may be soldered by using hydrochloric acid and ordinary solder. But it requires a good deal of heat, and the metal has a tendency to discolor when heat is applied. This discoloration cannot be removed. Brazing or welding by a professional is recommended where stainless steel presents an appearance problem. Welding and brazing are stronger than soldering.
