Understanding how to solder effectively can seem daunting to jewelers who are new to working with a torch. Following the five steps below will ensure strong, long-lasting joints on every soldering project you complete.
Solder won’t flow on a dirty or greasy surface. Use a de-greasing detergent cleaner and an abrasive pad, or an abrasive such as pumice powder to remove dirt or grease from the metal being soldered. Rinse thoroughly after cleaning. You can also steam-clean the workpieces.
Components, findings and joints must fit tightly together with no air space in between. Gaps in joints and poorly matched junctures between parts create a poor solder joint, which could result in pitting of the solder or in a weak joint that could break. Occasionally, solder simply will not flow into a poor-fitting area. Never use solder to fill in gaps or spaces.
Flux prepares the metal surface to receive the fluid solder. When applying flux, make sure it is in contact with the solder at all times and that it touches both metal parts being joined. Some self-pickling fluxes also help dissolve oxides. Keeping the joint oxide-free is important for creating the ideal soldering surface.
Use either a neutral flame (equal parts oxygen and gas) or a reducing flame (more gas than oxygen). The metal adjacent to the joint must reach the necessary temperature before solder will flow. First concentrate the heat on the surrounding surface, then on the joint to be soldered. Remember, solder flows to the hottest part of the surface and toward the flame. Use the least amount of solder needed to make a good joint. Do not flood the joint with solder.
After soldering, use a mild acid pickle to clean nonferrous metals. This removes oxides and other soldering residues prior to finishing. When storing solders, keep them free from dirt and grease. Sheet and wire solders may be cleaned to remove dirt or residue prior to use.