the wire has become to brittle and will snap when I try to use the
It’s probably not actually gotten brittle. Normally, you’d expect
the silver to be annealed, and might be too soft for some uses.
However, what may be happening is that if you form your balled ends
too slowly, too much of the wire above the balls may get too hot for
just annealing, and may have had the crystals grow in size, which
makes the wire weaker. Then, even though annealed, they may crack
when bent. So it’s not embrittlement, it’s over annealing of the
wire adjacent to the balls.
To avoid this, two things may help.
Work with a slightly hotter flame Less reducing. You don’t want it
actually oxidizing, but perhaps neutral in your oxygen/gas mix. If
you’re using an air/gas torch so you can’t adjust this, then simply
use a bigger flame to get it hotter. The idea is that you want to
form the balls more quickly, so the heat has less time to affect the
wire next to the balls. Quench the balls as soon as they’re formed,
in water, then pickle afterwards if needed.
Second, try holding the wire with only a little more than the amount
needed for the balled end to form extending past your tweezers. And
use thicker/wider tip tweezers, or the tweezer tips themselve may get
hot enough so the metal held in them gets hot, which would leave a
tweezer mark on the wire. Anyway, the tweezers act as a heat sink,
keeping more of the metal that isn’t actually in the flame, from over
heating. You’ll have to play with how much to extend the wire, since
if you hold it too close, and you’re not using an oxygen/gas torch,
you might have trouble actually getting the wire to melt.
A variation of this same idea, of protecting the wire next to the
ball from overheating, is to take a charcoal soldering block, and
drill a hole, the diameter of your wire, down through it deep enough
to hold the wire you’re using, which may mean all the way through the
block. Try to keep the hole size to the same as the wire. Now use a
small ball bur, the size of the balled up end you wish to end up
with, and open up a cup shaped depression at the exit of the hole. If
you stick your wire into this, with just the require amount
extending from the hole, into that depression, and hit it with your
torch, the end will melt to a ball, which will sink right down into
that depression, and no further. This has the advantage of giving you
really uniform ball sizes, properly centered; it won’t melt past that
point, and the charcoal block will protect the wire adjacent to the
ball from overheating. Be sure to flux the wire before melting it,
which speeds up the whole process, also a good thing.
Try it, and see if one or both of these ideas helps.
Another thought might have to do with your metal itself. If you’re
using one of the several tarnish resistant or fire scale resistant
versions of sterling, such as Sterlium, or Argentium, or others, know
that some of these can be more prone to being weaker or crumbly when
hot. If you flex a wire in these metals while it’s hot, you can get
cracking, which you might not notice till later, when you try to bend
it. If, when melting the balled up ends, your hand shakes the wire a
little, you may be causing that hot end to wave back and forth a
bit, and flex more than it is able to do without cracking. Standard
sterling silver doesn’t generally have this problem, but if you’re
using one of the new alloys, that may also be the root of the
problem. Not hand holding the wire, but using either the charcoal
block or a third hand tweezer to hold the wire, solves this last