This video features a tip on how to solder silver with flux and what to do when the flux balls up and won’t run.
When soldering silver and using hard or soft solder, I often find the solder balls up – it just refuses to jump no matter how long it’s under the flame. This is because the flux has burnt out and there is no medium through which the solder will jump (or run as some would say).
The ball of solder is hardened and I used to leave it, hoping I could sand it smooth after. However, when the piece goes into the pickling solution, the ball of solder often falls off and leaves the joint unstable, or the pieces completely separate. Recently I found out the best way is to add more liquid flux and then bring it back under the flame for another five to seven seconds. If the solder does not jump by then, I would add more flux and flame again; this usually works. I used to think that the reason I had trouble with this was the silver pieces were not clean so I would try to sand and clean the pieces feverishly, and I experimented with different sizes of solder. However, once I figured out it was the flux, my anxiety level with flame soldering calmed down immediately.
I took my silversmithing course with an old school purist and she used paste flux; like liquid paper, which must be applied with a brush. However, someone has since introduced me to liquid flux which I can apply with a needle squirt bottle and it’s made my life so much easier. Liquid flux is less messy and easier to apply and to reapply! Hope this helps!
Watch the video here: