Brian, Paste solder is no different from wire or sheet (cut into
pallions) solder. The difference is that the flux is already in the
paste, thus saving one step (or more) in the soldering process.
One difference is that when using paste solder, you DO NOT BACK OFF
your flame "to see what is happening", or to dry the flux.
In using a solder (paste or liquid) which requires a flux to be
added before the solder will flow, most people are taught to go "in
and out" with the flame so that the flux can be dried out and to not
disturb the pieces of solder that has been placed so carefully where
it is to be flowed. This is a good practice when using flux that is
liquid or paste (still containing water) at the beginning of the
soldering process. By drying the liquid or paste flux slowly, you
have assured yourself that the chip of solder will not move from its
originally designated placement. If you go in fast and hot, then the
water will boil off the chip and the chip will move, even jump
around, before it flows; landing it in an undesirable spot on the
With paste solder, you go in fast and hot, not backing off the
flame. The same rules apply to paste solder as to
pallions................ In the case of silver, bring the whole item
to temperature BEFORE you try to make the solder flow. If you use a
torch flame and go in and out, you will dissipate the flux in the
paste solder and get a crusty black crud on the piece. SO.........
technique is prepare your piece properly for soldering, put paste
solder where you want it, bring the piece to temperature but not
directly on the solder and then once you are seeing some activity
from the paste solder, bring the flame closer to the solder, but not
directly on it, and gently coax the solder to flow. Once it has
started to flow, you can direct it with heat to the exact spot, just
like any other solder. If by chance, the paste solder does ball up
and move, you can guide it gently back to your exact spot with a
solder pick, no need to stop and re-flux. A very interesting side
benefit to paste solder is that the join does not have to be as clean
as with the separate flux and pallions. The paste will cut through a
lot more "crud" in the join. Sometimes, when people have pickled and
rinsed a piece, there is still some chemical residue and they have
lots of trouble soldering. Paste solder will flow and make the join
even if the piece is not pristinely clean; a side benefit to the
paste. I do, however, recommend that your piece be prepared and
Several years back, I was in an enameling class where we were doing
soldering prior to doing champleve enameling on a piece. Many people
who were in that class did have problems with the black crustiness
happening. Once I was able to observe their technique of their
soldering, I saw that they were backing off as they soldered, not
bringing everything to a hot enough temperature for the solder to
flow. This backing off of the flame allowed the flux to dissipate and
not activate the solder itself. That is what causes the crusty black
residue. The flux had been dissipated (in the paste) and there is no
where to go but form the crust.......
Sometimes, the paste flux will still form a little bit of black, but
if the metal temperature is correct, this will quickly disappear and
the solder will flow.
Soldering is an acquired skill. Many excellent solderers still need
to adjust to the learning curve of a paste solder. As with any
technique, it is practice. Once you master it, you are well on your
way to enjoy using the paste solder.
If you are not happy with the product(s), after you try the method
described above, please feel free to contact me off list and I will
make arrangements to give you a refund.
The IT formula may have too high a melt for the copper you are
trying to solder, you might want to try the Eutectic formula since
you can enamel directly over that solder. It contains no zinc, so you
will not get any bubbles in the enamel when/if you enamel over that
solder. It is a perfect product if you are making pod forms that you
want to cover with enamel or dome shapes, put onto a disk. When
enameling on copper, you must be very careful to have the copper very
clean so as not to contaminate the enamel. The Eutectic paste solder
flows at F 1435 and contains both copper and silver, no zinc. The IT
flows at a higher temperature of F 1490.
I do hope I have found the problem and you will soon be on your way
to being proficient with the paste solder.
Unique Solutions, Inc.
Paste and Powder Solder for Jewelers and Metalsmiths