When I first started soldering, I would buy pre-made flux from Myron Toback on 47th St. One week however, I found myself out of flux and stuck in suburbia, so I had to hunt down an alternative.

Somewhere in my library of technical manuals I found a simple, yet effective recipe for flux. Mix powdered boric acid and 20 Mule Team Borax in a 3:1 ratio. Some people will dissolve this in denatured alcohol, other recipes call for ammonium chloride.

I have had a lot of luck with grinding the two powders together with the back of my soldering tweezers and then mixing up what I need with water in an old ceramic ashtray.

To use, I coat the area that I am soldering (the entire thing if it’s small) avoiding any areas that have previously been soldered. I use a small, inexpensive paintbrush.  I dry the flux with my torch, then I coat the solder in flux and place it on the join. If I do it right and work quickly enough, the cool, wet solder will stick to the dried flux and the solder won’t blow away in the flame. I might dab the edges with some additional flux, maybe.

Recently I tried to mix up some flux ahead of time and add some pieces of solder to it. I think if I was in my studio more often, I would have used this little batch up, but I found that it separated and the borax/boric powders formed a pan at the bottom of the jar. Left undisturbed, the solder eventually turned blue. I would have thought that the blue was from minerals in the tap water I used, but then I remembered that I had a crucible become coated in a beautiful, blue, glassy substance. I had sprinkled borax on some casting grain that I was trying to melt.