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Soldering two flat surfaces together

I’ve been given the challenge of soldering a few flattened sterling
eagle heads onto some commercial cigarette lighter cases. I’ve never
done anything like this before. I’m still mastering the art of using
the lovely H2O torch that came with the shop equipment. Is there a
trick to soldering one flat piece tightly against another flat piece
without putting holes in one or the other, or having solder show
around the edges? And can I solder sterling to plated brass? What
sort of solder should I use? I haven’t tried assembling these
particular parts yet…fortunately there is no immediate deadline, so
I have time to learn how to do it right (or chicken out and pass the
job along to someone else!).

–Kathy Johnson
Feathered Gems Jewelry

Kathy This is a routinary process for the Zuni or Hopi indians when
soldering two flat pieces together they call it metal overlay and in
order to get a better distribution of the solder on the entire
surface of the plate to be solder they use a method of filing silver
from a slug and mix it with flux preferably gel flux this is
basically the same principle of the commercial paste solders although
I would recommend the homemade one cause the lack of additives and
heavy metals like cadmium. When putting the two surfaces to be solder
be sure they are completely flat and match each other in surface
configuration to avoid air bags and voids or unsoldered areas and use
a big open flame to heat the entire piece to melt the solder and get
a clean join. And you going to have to replate the lighter upon
completion of the soldering depending in the thickness of the plating
and usually when silver soldering you have to sand both surfaces to
be solder. Marco

Dear Kathy, We solder many hand cut sterling initials on money clips
and key chains where the money clip or key chain is a polished,
finished item. My trick is to use Staybrite flux and solder. Cut a
small piece and practice how much it will take to adhere what you are
soldering. The trick comes in with the flux, I flux only one of the
items so the top piece being soldered will not float around on the
flux. Since I melt the solder on the initial to be soldered down that
piece already is fluxed and I don’t add any more. Overheating is the
enemy of soft solders. If it is not flowing STOP. Clean both pieces
(in a sonic if you have one) and reflux and reheat slowly. Hope this
helps. Sam Patania, Tucson

Hi Kathy, The key to soldering two flat pieces together is what’s
called sweat soldering. To do this start with the bottom flat piece
and place some pallions of solder in the place where you plan to put
the top piece. Just a few pieces should be sufficient. A little goes
a long way, as you know. And don’t forget to use flux. Now heat up
the bottom piece just until the solder starts to flow. Now place the
top piece in place, making sure it’s fluxed. Now heat up the two
pieces together. Watch the color of the metal as you will not be able
to see the solder. It should flow at about the same color temperature
as the bottom piece did alone.

Make sure that the two flat pieces are flush. If you are soldering a
coin, you may need to file flat the side to be soldered. Also, I’m
not sure how well plated metals solder. Sounds kinda iffy. Maybe
someone with more experience can address that issue. I do know that
regular brass and silver solder together rather well. but plated
brass? I dunno.

Happy Hollandaise and Seasoned Greenthings!
JoAnna Kelleher, owner
Pearl Exotics Trading Company
Phoenix, AZ where it’s a chilly 65 degrees!

I use a hot air gun and Tix solder to solder flat backed charms to
sterling money clips. It is relatively fast, and does not oxidize or
anneal the metal like a torch would.

Rick Hamilton

The technique I use for soldering two flat surfaces together is
called sweat soldering. This is where you coat the top piece with
flux and lay solder pellets about the same distance apart as the
width of the pellet. Melt the solder and move it around while it’s
fluid to coat as much of the piece as possible. Put the piece into
pickle while hot, and then sand it lightly after rinsing and drying.
Lay the solder-coated object on top of the to-be soldered
object-(gravity works for you) make sure they are flat, and heat
until you see the solder glisten around the edges. Now, as far as I
am concerned, I don’t think the brass plating will hold up. Find
out from your customer if they mind either losing the brass plating,
or having to pay to have the piece re-plated. Furthermore, are you
sure of what the metal is under the plating? If it is base metal,
disregard all I have said as I don’t have the faintest idea how
you’ll do this.

Cindy Leffler -Leffler Jewelry & Sculpture

 I don't think the brass plating will hold up.  Find out from your
customer if they mind either losing the brass plating, or having to
pay to have the piece re-plated.  Furthermore, are you sure of what
the metal is under the plating?  If it is base metal, disregard all
I have said as I don't have the faintest idea how you'll do this. 

As for the metal under the plating, if it IS base metal (e.g.,
copper and its alloys, brass, bronze, nickel-silver, etc.), it should
hard-solder very nicely. If it is “pot metal” (a low-melting
alloy), then the whole piece will melt while the flux is being warmed
up. It may be plated steel – test this in advance simply by holding
a magnet up to it. If it attracts, it’s iron or steel under the
plating; if there seems to be a very weak attraction, it may be

When tumble-polishing plated brass jump-rings, I have had the
experience that the top layer of brass wears off, exposing a grey
metal layer beneath. If I then dip the jump rings in nitric acid,
the grey layer comes off, to reveal solid brass beneath (I assume
that the outer layer was brass of a special composition – “Hamilton
Gold”?). I just mention this to illustrate the obvious – platings
on jewelry may be complicated. That’s why I never work with plated
metal. (Those plated jump-rings were useless to me.) HTH.

Judy Bjorkman