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Chill gel


#1

I recently made a brooch of sterling with a piece of glass and a
mexican fire opal. several weeks after I made the piece the pinback
that holds the stem came off. there was solder on both the pinback
and the brooch itself, so I know that the solder actually flowed
when I attached it, it wasn’t a matter of adhesion by flux. is it
possible that I created too much tension with my pliers when I
closed the sides of the pinback, or would there be another reason?
The other question is, could I safely re-solder the pinback with the
glass and fire opal in place if I use something like Rio Chill gel?


#2

Sounds like even though the solder flowed you still had a cold
solder joint. As for the Chill Gel idea, I’d recommend you forget
that and instead remove both the opal and the glass. Sorry. Jerry in
Kodiak


#3

Briefly, NO!!!

No matter what you use, you will not be able to preserve either the
opal or the glass from the effects of too much heat: they need to be
removed before you attempt to re-solder the piece.

Jim Small
Small Wonders Lapidary


#4

This is a job for a Sparkie II fusion welder. No heat, a bit tricky
with sterling findings, however.


#5

Hi Polly,

Since the majority of my training and experience is with stones,
I’ll tackle your second question first: whether you can or cannot
resolder your pin finding back onto the Mexican Opal piece depends
upon several (crucial) details that you haven’t told us. First, how
heavy is the silver you intend to solder it onto? Is it either
fabricated or cast from fairly substantial stock, or is it something
lighter, like 26 or 30 gauge? Second, where are the stone and the
solder joint to be located – i.e. how far apart are they? Are they
in close proximity, or even right next to one another? If so, no
amount of gel, goo, gunk or glop, no matter how fortified, will save
the stone from utter demolition. Mexican Opals are amongst the least
stable of the already-delicate Opal clan, because the majority of
them possess so much water vapor in their makeup. If heated to
anywhere near the boiling point of water (which is, of course, far
below the flow temperature of solder), this vapor expands,
shattering the stone. Add to this silver’s excellent thermal
conductivity and heat-sinking abilities (i.e. the need to heat most
or all of the workpiece in order to get a good flow) and chances are
pretty good that you’ll need to remove your stone before repairs can
commence.

The only possible way out of this that I can imagine would be if
your Opal were prong set and sitting on a long promontory, far away
from the pin catch: an area far enough away and small enough in
diameter that it would neither require direct heating nor be able to
draw enough heat away as to damage the stone. For example, if the
pin’s shape was that of a human hand, the damaged catch were located
at the wrist, and the Opal were prong-set at the middle finger tip,
you could probably get away with not removing the stone. In the end
it’ll come down to answering one question: which’ll cost you more,
the time, labor and cost of removing and resetting the stone, or
that of replacing it?

Next, about the solder joint that broke: what kind of soldering
agent did you use? Was it a hard solder, or something of lower
quality and/or flow temperature? And had you cleaned the two
surfaces before soldering them together? If not, or if only
partially, that could’ve weakened the bond, as well; while easy
solders won’t necessarily fill gaps any better than harder ones
will, they do seem more willing to flow onto unevenly cleaned ones,
especially when large amounts of solder are applied. Could that have
played a part in your joint’s failure? Last, but not least, (as
you’d suggested), how far did you “ask” the metal to move (via your
pliers), when assembling the pin stem? Like you’d said, it’s always
possible that you’d created a minor fissure during assembly, which
gave way, later. When you discover the real reason, please drop a
line and let me (or us) know what it turned out to be. 'Til then,

All my best,
Douglas Turet
Turet Design
P.O. Box 162
Arlington, MA 02476
Tel. (617) 325-5328
eFax (928) 222-0815
anotherbrightidea@hotmail.com