You need a torch to apply enough heat to get a solid weld. You don't need a fancy, expensive model - the type of propane or butane torch sold in a hardware store will do the job for you. You can use paste solder or solder sold in sheets, which must be cut into small pieces before use. For jump rings, it's probably easier to use paste solder, since it stays exactly where you put it. Paste solder is a mixture of solder, a flux, and a carrier (makes the mixture flow and stay where you put it). You can buy paste solder in a syringe, which makes it easy to apply with precision. Paste solders are sold with names such as hard, medium, easy, and super easy. The names have nothing to do with how easy it is to use these products. They indicate the temperature at which the solder melts. Hard solder melts at a high temperature and super easy solder melts at a low temperature. If the name of the solder is followed by a number, then that is the temperature at which the solder melts. Personally, I would recommend hard or medium solder for jump rings. You want the ends of the jump rings to melt and the solder to flow at approximately the same time. If the melting point of your solder is too low for your torch, the solder may flow away from the jump rings before the ends can fuse.
One of the quickest and easiest ways to solder jump rings is to set up an assembly line for yourself:
- Close all of the jump rings to be soldered so that their edges are flush with each other. Solder can't bridge gaps, but it will flow down the joint between jump ring edges. Place the jump rings in a row close together, but not touching, on a fire brick or soldering block. Line them up with all of their joints facing the same direction.
- If you have more than one row of jump rings, place additional rows below your first row, with about 1 inch separating each row.
- After all rings have been placed, apply the paste solder to the joints. Apply the solder to the inside of the rings, so it contacts the joint on both sides of the rings. The amount of solder you use should be about the thickness of the wire. Apply the solder to each ring until all have had solder applied.
- Turn the soldering block so that all of the joints are facing down or toward you.
- Light the torch and begin soldering, starting with the upper left ring (upper right if you are lefthanded), proceeding across the row until all of the rings in that row have been soldered. Apply the flame so that both the right and left sides of the joint are heated evenly until the solder flows. You should be able to watch the solder flow through the joint and come out on the front of the ring.
- After all of the jump rings have been soldered, you may find it convenient to collect them on a wire. Pickle the jump rings to remove any oxidation or flux residue. Neutralize the pickle by rinsing the jump rings in a water with a bit of baking soda (sodium bicarbonate).
Use a similar technique to solder jump rings on chains. In this case, each ring/link is done indivdually. The ring is held apart from the chain with pliers or a hemostat, solder paste is applied, and the link is held over the edge of the solder block (to help protect the rest of the chain from heat) and torched.