Jewelry 101: Flux

I'm writing a series of short articles on jewelry making basics, called Jewelry 101. You can click on Jewelry 101 under "categories" in the right-hand column to see all the articles (this one is the first). Even if you aren't interested in making your own jewelry, it might be interesting to learn a little bit about the basic tools and processes I use to create jewelry. Now, on to my first topic: flux. Flux is a liquid or paste applied to metal when heating the metal. There are many different kinds of flux on the market, and they all work for different temperature ranges. In jewelry making, when using a torch to solder or fuse metal, it is important to get a flux that is intended for use at very high temperatures. This means that flux sold for use with soldering irons probably will not withstand the amount of heat a torch gives off, so make sure that the flux you buy is appropriate for use with a torch. Flux protects silver from firescale while heating, and prevents oxidation of metal. It is always used when soldering, as the solder will not flow properly if flux is not applied to the solder & the area it should flow into. Flux can be applied with a paintbrush, and should be applied before heating the metal. As you heat the metal with your torch, the flux will bubble and then start to look glassy. If you notice that some of the metal is not covered with flux, you might want to add a little more and then re-heat the metal. Flux is almost always used when heating sterling silver, whether soldering, fusing, or annealing, because it helps prevent firescale from forming. It is not necessary to apply flux to fine silver when heating it, since fine silver does not get firescale. However, if fine silver is being joined with silver solder, you should apply flux to the solder and the spots that will be joined with solder. With Argentium sterling silver, some people don't use flux except for soldering, while some people also use flux for fusing. It is not necessary to use flux when annealing Argentium. In my personal experience, a tiny bit of flux (less than I'd use with regular sterling silver) helps a lot if I'm fusing or making ball-end headpins with Argentium. Flux is also used when soldering gold. Since I have limited experience soldering gold, I won't comment more on that right now. If you want to use silver solder to solder copper, using more flux seems to help, since copper oxidizes easily. I use liquid flux. A brand I like is Batterns, and I also like a very similar product called My-T-flux. Some jewelers prefer to use a paste flux, but I find that it's harder for me to see what I'm doing if I use paste flux. Whatever you decide, I recommend buying flux from a jewelry supply company - and make sure you get one that is intended for use with a torch. I've heard that people have had success making a paste flux from denatured alcohol and borax, but I've never tried this myself. After you complete your soldering/fusing/annealing, you might notice that there is some glassy flux residue all over the metal. This can be removed by soaking the metal in an acidic solution known as pickle. I'll be writing about pickle in a future article, so stay tuned!