"Heather Coleman" wrote in message
...


Hi :-)

I was chatting on this group back in November 20th of 2004 about working
with gold and have another question that someone might know something
about and want to comment on.

I will have to explain my story in order for someone to get the idea of
what I have been up to... I am no professional so bear with me! :-)

About 4 years back I took two of my hall-marked gold rings of what I
believed to be 18ct gold and melted them in a crucible in my pottery kiln
at about 1300 deg Cent...
I knew nothing at the time about working with gold and so assumed I would
get a blob of gold that I could experiment with as back then I could not
afford to buy new.

Well... if I had used a flux it would have helped but my crucible broke
and I ended up with several scattered blobs of good looking gold and a
load of very nice rich coloured red and black glassy material where I
assumed the copper part from the gold had merged with the glaze that was
on my homemade crucible!

[That would mostly be the flux, with perhaps a little color from the metal
oxides.]

Next thing I decided to do (still at that time with little knowledge) was
take the dozen or so bits of broken crucible out into my garden and blow
torch them until the metallic gold ran off them. I scattered some flux on
to help them run and eventually after a long time I managed to salvage a
blob of gold from the mess I had created.

I think after that I had a go at beating the blob into a disc which worked
and then the project got left for another year or so.

When I decided to finally do something with this blob I re-melted it AGAIN
in a small pure porcelain (unglazed) crucible that I made with some flux
and then beat it into a ring... this time I managed to create it into a
small doughnut shape that I beat on a ring making stake and I almost got
it to a ring that I could wear but because I did not keep annealing it
often enough it split...

So the gold went back and got remelted yet again!

Last week, I decided to have another go :-) and this time I took the blob
and reformed it as a little doughnut (blob with a hole in the middle) and
this time I managed to form a single ring which I later sliced down the
middle and made two beautiful narrow rings from. The appearance is very
rugged with beat marks all over and is exactly what I wanted to achieve.

Now this brings me on to my questions...

While making the final rings I annealed the metal very often to soften
it... sometimes I quenched it in acid while it was still very hot and the
metal surface when beaten on the stake was very silver coloured, not gold
at all (?!)
Other times I quenched it in acid when it was much cooler and the surface
was a pale golden colour.

[Quenching in acid will create toxic fumes, and can splash corrosive fluid
around. Steel tools anywhere in the vicinity can experience accellerated
rusting. Most jewelers use a milder pickle solution based on sodium
bisulphate ("Sparex" is one brand - it's also sold as swimming pool Ph
adjuster), which works almost as well with fewer bad effects.]

The final colour of the rings (because the last time I annealed them I did
not quench but left the very black oxide on them) is a deep rich
gold/copper colour which is rather nice.

[The acid quenching may have been depleting the copper at the surface.]

Am I right in saying that this is because the gold still has a lot of
copper in it and the copper oxides are trapped in the structure of the
gold?

[Not the oxides, but the metal itself.]

When I quenched in acid from VERY hot (the glow only just died away) the
colour went almost completely silver which was what puzzled me the most...
I assume this is because the gold crystalised at it's surface due to rapid
cooling and so it was reflecting the light in the surface layers?

[I don't know; I've never done that.]

And I assume that if I wanted to change the colour back to the best gold
that I can achieve with this overworked material I would have to reheat
and quench them at a much lower temperature?

[That seems to have worked...]


Finally, this is a really daft question to ask but is this how different
coloured golds like red and white etc. are created?

[No, that's done by alloying with different metals.]

In conclusion... those two original rings have certainly been through the
fires, I have learned a few things the hard way, but I now have two lovely
rings that I should enjoy for a few more years to come.

regards
Heather

[At least you didn't hurt yourself; that's the important thing. If you do
this again, use a torch, not your pottery kiln, and a real crucible. Flux is
good, but don't use too much - it's meant to cover the gold during melting,
but is just in the way during pouring, and it can make inclusions if it gets
mixed into the metal. Ingots are inherently rather porous, use a
purpose-made jeweler's ingot mold to get the best ones you can. Anneal by
heating to cherry red and quenching immediately; with high-karat gold you
don't need to use acid or even pickle - water will do.]

Andrew Werby
www.unitedartworks.com