The first step in soldering gold is to dip the piece of jewelry into a solution of boric acid and alcohol before lighting it. Learn about soldering gold with help from a bench jeweler and gemologist in this free video on soldering jewelry.
Somebody asked how to solder jewelry metal, which is generally gold and it's your lucky day because I have something that needs to be soldered right now. What I've got is a 14 carat gold wedding band that needs to be sized down. So what I did, was I cut a piece out of it and now the first thing I have to do is bring these two pieces together and I'm going to use some specialty bending pliers to bring these two pieces of metal together just like that. Now we've got a good smooth line here. OK, the very first thing you want to do when you're soldering gold, is you want to dip your ring into a solution of boric acid and alcohol and then you want to light it. What this does, boric acid is the white compound that you see on the ring and boric acid keeps oxidation from occurring everywhere except where you do your solder work and I don't mind if it oxidizes and discolors right here where I'm going to solder it because I have to clean and polish that anyway, but I really don't want to clean and polish everything else. And that's what the boric acid and alcohol does. So next thing is I'm going to put my green flux on the joint which helps the solder flow and then I'm going to take my 14 carat yellow gold easy flow plumb solder, I'm going to flow my solder in a ball and pick it up on my solder pick like this. You always have to remember when you're soldering gold or silver or platinum that heat is going to go to the coldest point. So if I put my torch here, all of my heat is going down here because this is the coldest point. Well because I want control up here, I want this to be the coldest point of the ring, so this is where I'll put my torch last, not first. So what I'm going to is I'm going to come down here and I'm going to heat the bottom of this up. And you can see my flux starting to bubble up on the top here. So once all of this is hot, now I'm going to be able to control what I'm doing up here. So I'm going to put my solder on here and now watch it. It's just going to all of the sudden, it's just going to disappear. I'm going to make sure I get both sides of my ring equally hot and there the solder went through the joint. Now if I pull my torch underneath, solder goes to the hottest point. So if I make under the ring the hottest point, my solder will flow all the way through that point just like it did. And now, look at it, that is a very clean solder joint so let's dip it in the boric acid and cool it. Tap it round. Now as you can see that it's discolored right here, but nowhere else on the ring is it discolored. This is just some boric acid which will come off here in the polishing. But now what we want to do is let's run a file across that and see what it looks like. And that is how you solder gold jewelry.