Bench Tips from Stewarts International School for Jewelers
CHAIN REPAIR by Jim Stewart
Take time to clean the chain because the oils and hairspray that get inside the hollow links
can affect the ability of solder to flow. You may have to clean the chain using a tablespoon
of Red Devil Lye to a few cups of water at 180F. You will need ventilation while doing
this. You can cut through one link on both sides using an ultra thin cutoff disc or you
can lay the gold chain down on a flat piece of copper and cut the links with an X-ACTO knife.
It is less costly to replace an X-ACTO blade than a flush side cutting pliers. Now weave
links together and solder using paste solder. Paste solder is not necessary but it is a little faster.
Tips from Unqiue solutions
Pits in your solder joins are from the solder not melting completely OR... you have not used enough solder at that particular place. Pits can also come from the areas not being clean at the spot where the pits happen. Not being clean enough is not usually a problem with paste solder, by the way, as it is has much more "self cleaning" ability than many other fluxes by the nature of the flux contained in the paste.
The trick to avoid pitting is to heat the metal around the area and not directly on the solder and thus dissipating the flux. You need to bring the metal to the melting temperature required by the grade of solder you are using. You then have to continue heating past the melt temperature until your reach the flow temperature of the solder. At the point where it is just about to flow, you can direct your flame to the area you are concentrating on joining and remember that solder flows toward the heat. You can draw the solder through the join and make it a very smooth seam. If you are getting some pitted appearance when the solder is shiny (liquid flow stage) and the solder is not filing in the gaps and you are seeing (pits), then simply use a soldering pick to go over the seam at that point and smooth out the solder so it will fill in those gaps while the solder is still hot and flowing. Note that if the seam (join) is not tight, no matter what, the solder will not entirely fill the gap and you will have a space.
Did you know that you can pick solder with paste solder? Simply extrude (from a syringe) and place a small amount on the tip of a soldering pick. After the solder is on the pick, just apply a small amount of heat to the pick up from the tip so the solder does not roll off, but forms a small ball at the tip of the pick. Works every time once you get the hang of it. If you are using some paste solder from a jar, you can heat the pick in advance, dip into the paste solder in the jar and pick up a very small amount of the tip. You may have to heat a little more to get the solder to ball. If the solder ball is not exactly at the end, you can use the side of the torch tip to move the solder to the end of the pick. Tricky but once you master it, you will like the new technique.