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Stubborn melting

#1

Have you ever had a piece of metal absolutely refuse to melt? Or
rather, it appears to have melted, but it doesn’t ball up. It’s as
though there is an outer skin holding back the molten metal.

This has happened several times with sterling wire (16ga) that I am
using to make chain clasps. The ends of the wire need to be melted
until they ball up. I held the end in a propane flame for what
seemed like a long time, but it never flowed or balled up. I could
tell that it was melted below the surface, though, because the wire
got skinnier about 3/8" from the end. Eventually it broke off at the
skinny part–but the broken-off part was still the same shape!

I had applied Prip’s flux to the wire before heating it. Could this
have created a skin of some sort, or increased the surface tension
so the metal couldn’t flow?

Janet

#2

Janet, You said you held the wire in a propane flame for a long time.
What kind of propane flame? If you are using only propane without
oxygen, and if the flame is very wide and/or soft, that might be part
of your problem. 16ga wire is not very heavy and should melt very
easily…however, if the flame is bushy (maybe even at reducing
level), you are not getting the right concentration of heat at the
tip of the wire. In short, most of the heat is simply bypassing the
thin wire.

To get a ball on the end of wire, first use a sharp oxydizing flame
(hard blue) and point the blue cone at the tip of the wire. It is
best to use propane w/02 or acetylene w/02 to get the heat required.
The Prip’s flux should not interfer with the melt but, before placing
the wire in the flame, dip the tip into self-pickling flux such as
Batterns. This will insure the area is very clean and help the ball
form. When you get the size ball you want, slowly move the torch
away keeping the tip on the ball for a few seconds. This keeps the
ball and attached wire hot so as the ball begins to cool, it can draw
metal from the wire. If you remove the torch too quickly the ball
will develop ‘dimples’ because is cannot draw from the wire. This is
the same as having a nice ‘button’ when casting…the button acts as
a source of extra metal for the casting to draw on.

Hope that helps, Cheers from Don at The Charles Bell Studio in
chilly SOFL where simple elegance IS fine jewelry! @coralnut2

#3

Hi, Janet, First, I think the technique you’re looking for is what I
(and many others) call “pick soldering”. Here’s how you do it: After
your joint is fluxed and assembled, lay a few little or tiny pieces
of solder on a fireproof surface where you 1. can find them again
and 2. won’t stick your elbow on them. Set out more than you think
you need, because you don’t want to stop in the middle to find more.
Separate them about an inch. Heat the first one until it balls up,
then bring a tungston or titanium solder pick to touch the solder.
It should pick it up. If not, keep trying until it does. Then heat
the joint until it is at/near soldering temp. Bring the pick with
the solder in and touch the ball of solder to the exact spot you
want it. You can hold it there a bit if necessary, until it flows.
This is the ideal way to solder tiny joints like jump rings, among
others. Incidentally, I have a fairly bad tremor, and I can tell
you, you can learn to cross-brace your hands so that you can do
detailed work accurately. Second, if you are unable to ball up the
end of a wire, you may need a hotter flame, because the rest of the
piece is absorbing heat too fast. But try this before you go out
shopping: Hold the wire in the flame with the cut end facing down.
The wire should be just outside the inner bright blue cone,
and–note this-- the tip of the wire should be at the bottom edge of
the outer, pale blue part of the flame. This means that as much of
the wire as possible is within the flame. This is counterintuitive,
but it works. If it doesn’t fix your difficulty, then maybe somebody
else can…

–No?