I’m interested in sweat soldering three pieces of sterling silver
onto a silver silver back plate - in other words, overlay. The pieces
are all flat. I have problems with the top pieces moving around after
the heat is applied. Perhaps I use too much flux, or my flux is too
wet, or I don’t dry it sufficiently. In any case, it happens.
For this particular piece I want to keep the gaps between the pieces
consistent. If they all three move relative to the backplate, that
is fine.
But I don’t want them to move relative to each other.
So I was wondering if there is something I could use as a spacer
that would not get soldered down but also would not act as a
troublesome heat sink.
The only idea I have so far is to buy a sheet of Ti from RioGrande
and saw out 1/8" x 1/8" squares and place them between the pieces of
sterling to create and maintain a 1/8" gap. If the pieces start to
move under the heat I can use my pick to push them back together so
they are touching the Ti squares.
Make sure that your flux is completely dried before you apply the
solder. Bring it up to heat and then apply the solder at the last
moments. You may also have to use a pick to hold the piece in place
until the solder sets. Finally, you could use different melting
point solders and solder each one separately. I am sure that others
have additional ideas. Good luck. Rob
Ti would work, in that it doesn’t solder down. But maybe better to
try using boric acid and alcohol as your flux, and/or using
"stitches" to hold your pieces in place. To do this, use a sharp
graver to lift a tiny curl of metal fron under the applique area to
JUST outside the line of where it will sit. The tiny spike of metal
will anchor the overlay like a teensy prong. With a little practice,
this is quick and easy.
Out of curiousity from the uninitiated, how does one sweat solder
pieces together, but have a gap? I thought “sweat soldering” meant
they laid atop one another with no gappage. I’d love to know more
about this.
I was wondering if there is something I could use as a spacer that
would not get soldered down but also would not act as a troublesome
heat sink.
The only idea I have so far is to buy a sheet of Ti from RioGrande
and saw out 1/8" x 1/8" squares and place them between the pieces
of sterling to create and maintain a 1/8" gap. If the pieces start
to move under the heat I can use my pick to push them back together
so they are touching the Ti squares."
It seems that Titanium would act as a heat sink, at least to some
degree. What about mica? It can be peeled to yield sheets of various
thicknesses, doesn’t conduct heat, and it’s fairly impervious to
soldering temperatures - mica’s often used as a base for plique a
jour enameling. It can be cut with scissors to the sizes required;
no need for sawing.
Could you lay out all the pieces, in place where you want them, on a
warm hot-plate/cup warmer to allow the flux to dry completely? Then
the pieces should stay put…
Marie - I’ve had a good bit of luck with sweat soldering using
powdered solder. You apply white paste flux, let it dry, then
sprinkle the pieces to be soldered with the powdered solder, tapping
off the excess (do this all over a piece of baking parchment) Have
the flux on your back plate prepared with white flux, dried. Then
simply place the pieces where you want them, heating from under the
back plate. I haven’t had the parts move this way.
Another way is to “tin” the 3 parts with solder using minimal
solder, pickle and dry. Then place them on the back plate where you
want them. Put the whole assembly on an electric griddle, cold. Using
a hypodermic needle enabled yellow flux dispenser, put a small amount
at the edge of each piece just touching the backplate at the point
where the top piece sits.
Capillary action will take the flux under the three parts. Now
slowly, very slowly, bring up the temp of the griddle to about 200F.
Let the metal sit and dry for 10 to 15 minutes. Then use your torch
to heat the backplate and the solder will flow and the pieces will
stay put.
White flux - Handy Flux Paste - from everybody
Yellow liquid flux - I use My-T-flux - Rio Grande
Liquid flux applicator - 504005 Rio Grande Needle tip flux dispenser
is this an application where precious metal clay would be useful? A
thin application of PMC between the 2pieces, dry and sinter, then
flux in the solder into the porous PMC?
I’ve been waiting to see if the more experienced jewelers mention
using graphite as a spacer - “lead” for old fashioned pencil, that
is.
It can work to keep areas apart, according to what I’ve read. Things
like holding the knuckles of a hinge in place during soldering. I
remember using pencil lead for holding things apart quite some time
ago. Has anyone experience with it?
I've been waiting to see if the more experienced jewelers mention
using graphite as a spacer - "lead" for old fashioned pencil, that
is. It can work to keep areas apart, according to what I've read.
Graphite is not really used as a spacer to hold pieces apart. I
believe it just keeps the solder from getting on the hinge edges.
Ideally, hinges should be as close as possible (touching).