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Getting silver solder off a copper surface


#1

I’m taking a metal working class. My project is a large copper
pendant, formed in the hydraulic press, chased details, soldered onto
a copper sheet back with a sawed opening that gives a view of a small
silver heart charm soldered inside. It’s an experimental piece using
the techniques I’ve been learning in class.

The teacher wanted me to solder the front to the back using stick
soldering (using a long piece of wire solder and drawing the melted
solder along the seam with the torch) instead of pick soldering with
paillions like I’m used to. And it was my first time using an
acetylene torch too. Huge learning curve for me; I should have
practiced on something else first.

Anyway, now there’s silver solder all over the curved, chased front
of the piece.

I can’t copper plate it in used pickle because of the silver charm
inside (can’t reach the charm to clean it off again). Plus, some of
the solder mess isn’t smooth.

What’s the best/easiest way to get the excess solder off this thing?

Kathy Johnson
Feathered Gems Jewelry
www.featheredgems.com


#2

This is just an idea, and you need to double-check it for safety
first, because I haven’t!

Is it possible to put a wrapper around the charm that the pickle
would ignore, then remove the wrapper? An example might be a rubber
balloon.

(Or some kind of coating that wouldn’t react to the pickle, but
would melt off without causing oxidation or other staining.)

That way, you could use the used pickle with a bit of steel in it.

Or probably better, maybe you just do one side of the piece at a
time, being very careful not to let the charm get into the pickle,
maybe by tying it up?


#3

A very careful and tedious application of files, sandpaper, and
rubberized abrasive wheels are your best bet.

Without seeing the piece I couldn’t say for certain, but I’d bet if
you were clever about it, once the excess solder was smoothed down
you might be able to plate the piece bit by bit by dunking it in just
enough to cover one section at a time, but not so deep as to let the
pickle hit the silver.

For the future, it’s the very best idea to just not put solder where
you don’t want it. Second best would be to mask off areas that must
remain free of solder with something that will make the metal dirty
enough to keep the solder from flowing. There are professional
solutions called anti-flux, but yellow ochre or water based whiteout
work just as well. I’ve heard that graphite pencil lead can be used
too, but I haven’t tried it.

Willis


#4

Hello Kathy,

In order to get the silver solder off the copper, first take,
Soder-wick (copper woven wire), put flux onto the copper weave and on
the copper item.

You will need a soldering iron (high heat) or you can use a torch
with a lower heat. Take your solder pick and press the wick against
the copper, holding it in place with the pick, heat, moving fast.
Repeat to remove the excess solder. Be sure to pull the wick toward
the edge of the copper. You can see the wick take the solder off the
copper.

You will have a very thin layer of solder left on the copper. This
can be removed with a very sharp exacto knife scraping lightly or use
a brass brush or craytex wheel very lightly.

Then buff, lightly.

If you have a scope, scrape using the scope so you can see how
lightly you are scraping.

Soder- wick can be bought at Harbor Freight or hobby store.

I have wicked off silver solder successfully without making a larger
mess.

Veva


#5

Hi Kathy,

Step one, shoot your teacher. There are times for stick soldering
practice. That wasn’t one of them. (speaking as a teacher, but
with my tongue mostly in cheek, mind you.) A better bet would have
been to either put slugs of solder on the inside of the piece, and
draw them through with the torch, or to pre-tin the joint, and melt
it in place. Either would have left you with less mess, and much less
risk of making a huge mess.

Meanwhile, depending on how detailed your surface is, files anywhere
you can get them to fit, in progressively finer grades. For
convoluted surfaces, I’m quite fond of snap-on disks. They’re the
little 1" dia. sandpaper disks with the square centered brass
grommets. You snap them onto special mandrels, and sand with them.
They die quick, but they’re incredibly useful, and come in all sorts
of grits. (AKA Moore’s disks.) The nice thing about them is that you
can flex them as they spin, to get into all sorts of concave areas,
and feather your cuts.

For really serious cutting into detailed areas, or delicate solder
removal, nothing beats the right engraving tool to fit the shape.
The problems are twofold however: knowing how to properly sharpen the
engraver, and then how to cut with it once you do. In the long run,
knowing how to use an engraver is incredibly useful for all sorts of
things, but it’s not a skill you can pick up in a hurry, or while
you’re desperate to finish something. It takes practice, not
desperation. So if you don’t already know how to use them, start
pondering and practicing. (the two most useful for solder cleanup are
flats of various widths, and an ongilette set up British style as a
spit-stick. )

Hope this helps, at least a little.

Regards,
Brian Meek.


#6

Kathy,

My metallurgical understanding of the process, which may be flawed
(James Binnion can you help?), is that, at just over soldering
temperature, and with the melted solder at the interface acting as an
initiator (picture it as acting like road salt on ice), the copper
and silver will alloy together and that the alloy thus formed melts
at a lower temperature than either of the two parent metals. You are,
in effect, making a low melting point solder, of a silverish color,
which will avidly flood onto any surface that presents itself.

Early on when I first started with the copper/silver combination I
wanted on one project to solder short plugs of copper wire into a
1.5mm thick silver plate such that they would stand just high enough
over the plate that I could then hammer them down into a flared head
rivet effect. I drilled holes in the plate, carefully matching
diameters such that when the plugs went in they were tight tight
tight. They werent going to go anywhere. Then I fluxed and soldered.
With about a dozen plugs in the plate it was tricky and time
consuming to push all the little solder snippets into position. Too
time consuming: the piece got over hot, and suddenly before my
astonished eyes a bright line of melt formed around each plug and
each and every one which moments before had fit so tightly fell
through its hole and out through the other side of the plate, all in
unison, as if they had been lubricated and squirted through.That was
instructive.

So heat control is important. I use india ink as an anti-flux. In
conjunction with heat control it works quite well. The flux
considers the india ink as an impurity to be dissolved. Too much time
at soldering temperature gives it longer opportunity to do that.
Another trick is to undercut at the interface. If for example you are
soldering a silver plate onto a copper base putting a slight bevel on
the bottom edges of the silver will help to contain the solder in
the joint.

Cheers all
Hans Durstling
at this moment in Moncton Canada -
but who knows what tomorrow may bring