Help with Sweat Soldering

I am trying to solder a pierced silver pendant on to a thin solid
flat back, also silver. I have placed silver solder paste on the
pierced piece and heated it until the solder started to run, then let
it cool. I then placed the two pieces together and heated them
again. It’s not working though, the pieces are not at all firmly
joined. Any help would be much appreciated.

Many Thanks

Did you flux both pieces before you joined them for the final
soldering? After the solder has flowed on the first piece, be sure
to pickle it, neutralize in baking solder, rinse, dry, then flux
both pieces before joining them. Alma


Sweat soldering is not difficult but requires very careful
preparation. First, after piercing, anneal both the pierced piece and
the intended back. Put them onto a bench block and use a mallet to
insure they are both perfectly flat. Lightly sand the surfaces to be
mated. Wash both in alcohol to remove finger oils then Prip’s flux
all surfaces.

At this point, you have several choices. The first I would
recommend is …don’t use paste solder. I believe the flux in
paste solder has to bubble away and when it does, it causes vacant
areas around the remaining solder. These areas sometimes extend out
and away from the solder resulting in hollow places…and these may
even bubble up to preclude a good mate.

You can use any good self-pickling flux and cover the two surfaces
to be mated. Heat each in a direct flame to expand and relax the
flux. You can now use either pallions (snippets) or make some solder
dust by filing the edges lf sheet solder with a medium bastard file.
If you use snippets, place them randomly around the bottom surface of
the top sheet, heat until they melt and flow. You will now have a
surface with little welts of solder all over it. If you use solder
dust, scatter it evenly over the entire surface and heat the surface
enough for the flux to melt and hold the dust in place. Now place the
two surfaces together and position them.

At this point, I do not use a sweat stand! They eat heat worse than
a block of copper. I prefer to stand two charcoal blocks (or fire
bricks) on their side or on end and place the wire mat on them like a
bridge. Place the pieces to be sweat soldered onto the mat and heat
from underneath with a bushy reducing flame and keeping the flame
well away from them at first but gradually bringing it closer until
the piece begins to show red. Hold the torch at this point, moving
it around the entire base to insure even heating. The idea is to heat
the bottom sheet slightly more than the top but bring them to a high
enough temperature that the solder will flow. When it happens, you
will see the top piece slump slightly as it is ‘sucked’ down onto the
bottom sheet. You may also see a thin bright silver ribbon along the
edge between the two sheets. When the entire top sheet has
’slumped’, remove your torch and quench.

Sounds complicated but it is really quite simple.

Cheers from Don at The Charles Belle Studio in SOFL where simple
elegance IS fine jewelry! @coralnut1


I have had success with the following process:

I take the top piece, prior to piercing, flux it, heat it, and flood
the top with solder using hard wire solder. Sand the bottom lightly
to get rid of any lingering oxides or other crud. Pierce, flux, and
sweat to the bottom sheet.

Applying the solder before piercing works for me because it is easy
to flood the entire sheet with a piece of wire solder- then I don’t
have to worry about getting solder on the back of all the little
squigglies I have pierced.

Lee Einer


I’ve always used HARD solder. Keep heating the pieces until you see
the solder run. You may be afraid to heat it enough. Oh, and
another thing . . . the pieces must be totally flush so there are no
gaps between them. Heat evenly, or you may have pockets of air that
will cause the metal to bubble.

I thank U for your knowledges. I want to solder a cut out design of 22k gold, 0.5mm thick, onto silver plate, 1.3mm thick, 2" x 2" square and then do some shallow repousse of the gold parts. what kind of solder do I need.?

Silver solder, medium. Are you also looking for sweat soldering tips?

1 Like

Thank you. Yes more tips is good.

Lots of good tips so far. I can add a thought: when solder flows to the edge of the “sweated” piece, you see a line of solder at the 90 degree edge. It is called a meniscus and forms a curve, filling in the actual corner of the top piece meeting the base. There is no way to prevent this, but you can hide the line of solder, when seen straight on from the top. Just file the edges of the top piece so there is about a 45 degree overhang. The solder line will be hidden from view and the two pieces will appear more integrated.


Cool idea! Going to try this tomorrow. Thanks for sharing this @Lee_Einer1 :raised_hands:t4: