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Tumbler hardening sterling

#1

How long does it usually take to work harden annealed sterling
silver I’m a steel shot tumbler? 4 hours hasn’t done it, wondering
what my target should be

#2 
How long does it usually take to work harden annealed sterling
silver I'm a steel shot tumbler? 4 hours hasn't done it, wondering
what my target should be

Tumbling doesn’t harden the bulk of your silver items. It burnishes
a thin surface layer, and that compression of that thin surface layer
does harden the surface. But only the surface. This may be enough to
cause noticable hardening of things like thinner wires or even
thinner sheet, where that thin surface layer amounts to a significant
percentage of the whole. Earwires, for example. But even then, it’s
not the same as actually work hardening the metal by working the
whole piece of metal (for ear wires or simiilar wires, one easy
method is twisting the wire. The shape remains the same, straight and
unkinked. For shepards hooks, you bend them to shape after stiffening
them via twisting). What the tumbling will do is make the surface a
bit harder, and thus a bit more resistant to denting or wear. But the
effect, while useful, won’t really be percieved as a significant
hardening of the whole thing. Another process you can use with
sterling or a number of similar alloys like Argentium, continuum,
sterlium plus, etc, is heat treating. Called age or precipitation
hardening, this process does harden the whole piece of metal, often
to about the same state of hardness as “half hard”. But
metallurgically, you do not get the same structure as a work hardened
piece. It’s hardened for a different reason than work hardening, and
sometimes the result is hardening, but a greater degree of
brittleness than one gets with true work hardening, because the
crystal structure it gives is not the same. After heat treating, you
can still tumble, and get an even more improved surface toughness. As
to your original question, you cannot specify a single time, because
it will differ depending on the type and speed of your tumbler, the
amount of shot, the shot shapes, and the type of item you’re
tumbling. You’ll have to experiment to find how long is required to
get the result you want with each type of item you’re tumbling. But
again, don’t expect the tumbler to really work harden the whole
thing. It won’t.

Peter

#3

Tumblers only work harden the surface a few microns thick. A thin
enough layer that you can polish through it.

My go to silver alloy is Continuum by Stuller. I kiln harden it at
800F for 20-30 minutes and then quench while hot. It gets as hard and
as springy as 14 kt white gold. Much harder than sterling. It’s twice
the cost of sterling but I feel it’s totally worth it.

I love how it works and solders. I can make eyeglass temples only
1mm thick and they still hold up beautifully after two years of daily
wear.

It’s very slow to tarnish, solders and fuses like 18 kt gold and
bead sets beautifully. I just poured two ingots of Continuum
yesterday for sheet and wire. This is metal that I have melted, cast,
forged and re melted at least 10-12 times with out adding fresh
metal. It still works beautifully.

Really. I save money on refining costs and I can make much lighter
things that are still strong and wearable in the long run.

I always double my cost of materials at the wholesale level. So I
make more money if my materials cost more.

And no I do not work for Stuller or receive any financial gain for
recommending their product.

Have fun and make lots of jewelry.

Jo Haemer
timothywgreen.com

#4

Hi Peter,

For shepards hooks, you bend them to shape after stiffening them
via twisting). What the tumbling will do is make the surface a bit
harder, and thus a bit more resistant to denting or wear

That might be fine if the hooks are not subject to more heat but
does not work if, as I do, the eye of the hook is soldered shut when
attached to the dangle. I suppose it would be possible to solder on a
straight length of wire with an eye on the end and then twist and
bend into shape but this seems more than a little clunky. I usually
make my ear hooks in advance out of 50 mm of 0.8 mm ss wire with the
eye ready to solder. This means I get exactly 10 pairs of hooks per
metre of wire. I sometimes make a few out of a length of wire 5 mm
longer and leave room for a wrapped eye to attach to heat sensitive
dangles but I much prefer the neatness of soldered eyes.

To work harden the hooks after soldering I slightly flatten the top
of the curve of the hook with a soft face hammer on an anvil. Too
much may make the hooks uncomfortable to wear. I then tumble the
earrings in a vibratory tumbler with stainless steel shot for about 2
hours, longer if I forget to switch off the machine. I use a GyRoc
tumbler which is a lovely robust machine with plenty of power to
handle 2 kilograms of shot. The hooks feel noticeably more springy
after tumbling. I agree the tumbling won’t have much effect on the
hardness of the heavier parts.

Posts are a different matter. I twist these half a turn after they
are soldered and then compress an indent around the post with round
nose pliers to hold the butterfly in place.

All the best
Jennifer Gow

#5 
I suppose it would be possible to solder on a straight length of
wire with an eye on the end and then twist and bend into shape but
this seems more than a little clunky.

It’s really not necessary to change your process too much. You’re
still measuring a given length of wire. If you bend up, or solder on,
the end loop and bend the shepards hook, and then after adding the
dangle, solder shut the eye, you do get some annealing near the eye,
even if the wire started out drawn or twisted hard. But with a little
tweaking of your soldering setup, to heat sink most of the wire, you
can limit that annealed zone to just a few millimeters, which should
not then affect the function of the earwire. In fact, if it’s that
small a zone, as it can be, you could solder shut the eye, then grab
the eye and the wire, say 3 or 5 mm away, and twist the eye 180 or
360 degrees regaining any lost hardness. those first few millimeters
would not be hard to restore any curved bend to. Or, solder the eye
shut with the dangle, grab the eye and the end of the wire, and
twist, then shape the shepards hook. Different sequence, but unless
there’s something in the tools you use to shape the hook that is
blocked by the dangle, it should end up being the same process, just
different order. Of course, hammering the shepards hook as you do,
also works well, and ads a visually different element to the wire
that can be quite attractive. The main thing I’d want to ask is how
are you soldering the eye’s shut? If you’re using a big torch that
anneals more than the eye and a very short distance beyond it, even
with silver, you’re annealiing more of the wire than you need to.
The wire can start out the process drawn or twisted to the
desired/needed hardness, and you should be able to keep it there for
the most part. This, of course, kind of makes the whole discussion of
tumbling to harden ear wires a bit superfluous, though it’s always
good to have multiple tool options in the arsenal of ways to get
things done.

cheers
Peter

#6

Hi Peter,

The main thing I'd want to ask is how are you soldering the eye's
shut?

I use as small a flame as I can manage and work as quickly as
possible. In this case it’s with a #4 tip on my Little torch running
oxy propane using easy solder. I expect the wire gets annealed maybe
up to 12 mm from the eye.

Unfortunately silver is a good conductor of heat.

There is an additional issue of how hard ear hooks should be. If i
snagged and pulled out one of my earrings I would prefer the hook to
bend than to cut my ear lobe.

All the best
Jen

#7

Good choice. I just saw a patient last week who had to have an
earlobe repaired from such a tear. The plastic surgeon did a good
job, but still…