After reading a few articles explaining the use of Borax-based Flux for Soldering, I decided to try using it myself. I created a thin, milky paste of Borax powder mixed w/ normal tap water, I attempted to use a low temperature copper-based solder to join the two ends of a stainless steel ring.
I properly cleaned and joined the stainless steel ends of the ring so that they fix almost perfectly, I even roughed up the ends with a file so that the flowing solder would have a surface to cling to. I then used my flux brush to coat the joint thoroughly. After that, I added some commercial copper-based solder paste to the joint and proceeded to light my propane torch and begin firing.
Almost immediately, the thin protective coating of borax/water receded away from the joint. The solder nearly vaporized, leaving a thin black sooty-film all over the joint, at which point I turned off the torch. FML. I attempted to add a little more solder paste and a little more flux, but both sizzled off almost instantaneously. It was at this point I realized that something was wrong.
I cleaned and repeated the process again, to no avail. I began to get angry at the joint, solder and flux. I realize the melting point of this copper-based solder is probably very low and it was probably vaporized by the bright blue flame of my torch. I wrote down a few things that might have led to this nasty failure:
1. As stated before, the heat of the propane torch might have been too high. I hate this torch, it’s the portable kind that you buy from Home Depot or Lowe’s. I also have a micro-torch, powered by Butane, and a soldering iron.. the kind you plug into the electrical outlet. Maybe I should try using them for low-melting point items?
2. The Borax-based flux might have been too thin. It might be the wrong KIND of Borax, or maybe I just needed to use less water and more Borax. I don’t want to use my silver-solder flux since that’s used for higher temperature brazing. I dunno. I need help, lol.
3. The copper-bearing solder I used looked very strange, unlike any solder I’ve used in the past. It definitely doesn’t look like real metal, it looks like some kind of brownish paste that comes from a squeeze tube. Which is exactly what it is. Maybe I should use a rosin-core solder for soldering leaky pipes.
4. Maybe I just shouldn’t work with stainless steel. Nobody told me to work with it, and it’s definitely not in the Study Guide or the Repair Manual. I know it’s a ferrous metal with a melting temperature around 1400-1500 degrees Fahrenheit. Perhaps some gentle soul who has worked with stainless steel can give me an answer?
5. As I’ve posted before, in the jewelry repair & design forum, I would like to have the ability to to change the shape and intensity of my torch flame. Did I mention how much I hate my torch? I probably just don’t understand it but that’s because I’m very nervous working with this fire. I have had a long and torrid history with molotov cocktails, homemade flamethrowers, napalm and GI Joes. Does anyone else know where to find torch attachments for a regular portable Propane torch?
If your reading this, thank you very much in advance for even considering helping me. I don’t have much experience in soldering metal, especially metal that’s not listed in the books. Maybe I should just go back to reading & studying.
(Email me @ Wong_83@Hotmail.com if you have any helpful tips/hints or could even tutor me in jewelry creation. I would love to have the wealth of knowledge & experience to call on.)