If the solder had properly flowed, merely setting the pin would not
cause the failure you indicate. Without seeing the object, I would
guess one of two reasons:
One, you got what is known as a “cold join” where the solder flows
but primarily on only one of the surfaces. It is seemingly soldered
because because the solder began to flow on the second surface or the
parts are “glued” with flux - the latter is common with placing
findings as they heat so much more quickly than the object they are
being soldered to. While these will most often come loose in the
pickle, they sometimes survive that and pop apart later.
Two, at a critical moment after the soldered flowed, something moved
and the re-solidifying solder “broke” in the space between the two
Both of these flaws can usually be detected by louping your joins
after pickling. A good solder join, under magification, is a
complete, smooth fillet of solder running completely around the join.
Pin holes, cracks, and incomplete flows are all indicators of a bad
As for resolderng while the opal and glass are still in place, again
without seeing the item I would say no - especially when dealing
with sterling. With gold, if there is enough distance between the
solder point and the setting, and if the piece is not very heavy,
then you can roll the dice and spot heat. With silver’s superior
capacity to conduct heat you almost always have to heat the entire
piece before you can get a controlled flow at a given point - ie. a
pin back. Remember that even though you pack the stones in a heat
sink medium, the heat will travel right into it through the metal.
If the heat is coming faster than the heat sink can conduct it away,
the stone overheats.
Personally I would never heat a piece with opal - or turquoise - in
it without first removing the stone.
For what it’s worth,
L.F.Brown Goldwork, Inc.
17 Second St. East, #101
Kalispell, MT 59901