I have this problem and thought I would ask for some expert advice.
I fabricate quite a few Sterling silver half-round bands on a
regular basis... Sometimes I find that I get pitting
Andy, there are several things I can think of that might be causing
this… Overheating can do this, dirty solder, and contaminated flux
as well could cause the pitting. Just guessing, I’d vote for either
uneven heating causing one side of the joint to get hotter than the
other, causing a “boiling” of the solder or just general overheating.
Using the wrong flux or contaminated flux can do this too… if this
(and I would presume so for a ring joint) is a hard solder make sure
you have a hard soldering flux. It might be making the pitts. I
personally like the Batterns self pickleing.
Hope somehow this can help. Good luck. Dan.