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Melting a 21k Arabian gold bracelet


#1

A customer wants me to use her 21k bracelet as a source of gold for
a fabricated bezel-set ring and pendant. I’ll want to add more 24k
granules to increase the karat to 22k. but what problems might I get
when melting and reworking this bracelet metal?

I’ve uploaded a 800k image of it here:

http://www.adam.co.nz/875.jpg

Might this article contain deoxidizing agents in the alloy such as
silicone?

Thanks,
Brian

Auckland
New Zealand
www.adam.co.nz


#2
A customer wants me to use her 21k bracelet as a source of gold for
a fabricated bezel-set ring and pendant. I'll want to add more 24k
granules to increase the karat to 22k. but what problems might I
get when melting and reworking this bracelet metal? Might this
article contain deoxidizing agents in the alloy such as silicone? 

There should be no silicon in it, adding silicon to 18k or above gold
alloys causes brittleness so I doubt it will have any especially
since it appears to be wrought construction. Silicon is mostly used
for casting alloys below 14k. I think you will probably have no
trouble with it.

James Binnion
James Binnion Metal Arts


#3
I'll want to add more 24k granules to increase the karat to 22k.
but what problems might I get when melting and reworking this
bracelet metal? 

Probably none.

Might this article contain deoxidizing agents in the alloy such as
silicone? 

While nothing is impossible, it’s very unlikely. Even most 18K
alloys do not have deoxidizers, especially silicon. when any are
used, zinc is the more likely, and as I said, it’s rare. Not
generally needed for such high karat, and of course, 21K is even more
so. The main problem you’ll have is that, if you do the math, the
amount of fine gold you’ll need to add is surprisingly large compared
to the one Karat increase. And with the current cost of gold…

Cheers
Peter


#4
if you do the math, the amount of fine gold you'll need to add is
surprisingly large 

Maybe astonishingly large is better, Peter. I did the math, which
I’ll put below. If the bracelet weighs 1 ounce it will take another
1/2 ounce to raise it by one karat. That’s $550 @spot right at the
moment…

Gold needed= Original Weight x (Kt. Wanted — Original Karat)

24 ---- Karat Wanted

Or, for one ounce (in pennyweights)

Gold Needed = 20dwt. x (22kt-21kt) / 24-22kt, Or 20x1 divided by 2 =
10dwt. If the customer’s buying, it doesn’t mean much - seems like a
lot for a little, to me.


#5

Thanks Jim and Peter for your replies.

I think now that there’s something other than copper/silver in with
the gold in this ‘21k’ bracelet.

I’ve done a bit of an assessment of the parts of this bracelet and
notice these points. The catch is made from rectangular bar, is
stamped 21k, and curiously is also the more malleable component where
the metal colour is similar to 22ky. The very thin ‘coin’ parts which
seem to be mechanicly stamped are of a very hard alloy, and are so
hard it’s at the cost of malleability. Torch heating produced a very
blue/ultramarine colour at first. When ‘annealed’ there was little
difference in bendability, and cracked when bent almost in half.
Post-anneal quenched in water the metal is a deep blue-black.

A small ingot (poured Satsuo Ando method into water) produced a
cleanish button with a single large bubble in the top. Sawed in half
and rolled it made a very tough 0.5mm piece of sheet metal with some
(but not bad) edge deterioration. With the other half of the button I
rolled out a reasonable piece of 1.8mm square rod. But again it’s
nothing like as malleable as any other 22kr I make.

It’s only useable for ring shanks, bezel bearer and such jobs.

Has anyone else experienced this kind of metal?

Brian
www.adam.co.nz


#6

The gold was useable, to a point. So the weekend was successful. 19
hours (over 4 days) of tuition is documented heRe:

http://www.adam.co.nz/takako

Thanks for those who wrote (here and privately) with comments about
the 21k gold bracelet we were to melt up for source metal. It was a
nightmare, as the 21k metal did not anneal to much softer than say,
14k or even 9k.

There is something in this metal than makes it tough, and gives it a
blue colouring in the surface oxide. It pickled out well enough and
worked enough for the ring shank.

Brian
www.adam.co.nz


#7
There is something in this metal than makes it tough, and gives it
a blue colouring in the surface oxide. It pickled out well enough
and worked enough for the ring shank. 

The blue is almost certainly a signature of cobalt additions to the
gold.