Today we will look at a few tips on soldering and for the example, I will size a silver ring. First, figure out what size the ring is, and what size you need it to be. For each size difference is approx 2.4mm.
In this example, I will size a ring down, so I marked the ring and cut the ring using a 3/0 saw blade and supporting the ring with a ring jig.
I cut just inside the marks I made to allow room for filing. I use an Equalling Escapement File to file the inside of the shank, what this file does is makes sure the two ends are parallel to one another so there are no gaps in the soldering process. Gaps usually means pits in your solder joint.
Next, I make sure the two ends are touching with no gaps, if the top of the ring is strong enough, I will twist the shank a bit and bend the ring past center, to compensate for the “spring” in the metal. You want to make sure the two ends match very close.
Now, clean the solder joint very well, if you have an ultrasonic cleaner and a steamer, that would do the job well, but if not, soap, water, and a soft tooth brush will work. Protect the ring’s finish by dipping and “swirling” the ring in a mixture of Denatured Alcohol and Powdered Boric Acid. I always keep this mixture around and dip everything in it before soldering. I keep it mixed, about 1-2 tablespoons of boric acid to 1 oz. of alcohol. I keep it in an old baby food jar. works great on both gold and silver. Let air dry before soldering, you will notice it will turn your jewelry “white”, this is good, it is a thin coating of protective boric acid which will help keep fire scale down.
Next, I add flux and solder. I use Handy Flux, a brazing flux that works great, especially on silver, but I use it on gold as well. I also keep this in a baby food jar, along with a silver wire to apply the flux. Coat the solder joint well. Heat the piece until the flux just stops “bubbling”, then add a small piece of solder with a soldering pick. I use a TITANIUM SOLDER PICK, the solder doesn’t melt to the titanium like it will to steel. I just barely dip the tip into the jar of flux and pick up the piece of solder with the pick, then apply it to the top of the solder joint. I used medium SILVER SHEET SOLDER and I cut it as needed. You will be tempted to want to use a bunch, but you don’t need a lot. See how much I used for this application.
Now comes the FIRE!! I use a Smith Mini Torch and have used one for years. The gas I use is propane and oxygen, but you can use Acetylene or Natural Gas. I like the propane because it is easy to get, and it is a much cleaner gas to use. Acetylene produces black smoke and “floaties”. I use the #5 tip that comes with the torch, in fact I drill it out a bit to give me more heat on larger projects. I use the same regulator on the propane that I used to use on acetylene. You will want to get a flame that is not too “bushy” and not too “sharp and pointy”. The flame in the image is what you want to aim for.
I mentioned that you wanted to apply the solder to the top, this is because we will be applying the heat to the bottom of the solder joint. One of the biggest mistakes many jewelers make is applying the heat to the solder, this is a NO-NO. You always want to apply the torch heat to the opposite side of the solder joint because solder is drawn to heat, like a moth to a flame. When you do this, you “draw” the solder THROUGH the solder joint, making a stronger joint with less pits. Also if you melt the solder first, you “boil” the solder, changing the characteristics of the alloys in the solder, making it flow less and more brittle.
After soldering, place piece in a pickling solution. I use Sparex which will help remove fire scale as well. I use a very small CERAMIC LINED CROCK POT to heat the pickling solution. Heating the solution makes it work a lot quicker.
We will get a lot deeper into soldering in the future, I hope this helps.