Pure gold

Jewelry Discussion
1

hi all, some time ago i asked about an alloy called 'pure gold’
and told everyone that i would share my experience working with
it.

pure gold is available in two options, both are .9985 pure gold:
alloy ‘a’ and alloy ‘c’.

alloy A is meant for fabrication and/or casting under vacuum.
one can achieve greater hardness with it than alloy C. i’ve
fabricated comfort fit bands with this alloy and it does indeed
get very hard after work hardening (no great hardening occurs
during working) then age hardening for about 3 hours (at 300C).
exactly how much harder alloy A is than alloy C, i don’t know
because the info suppplied only says 180 hv and does not
specify. 180 hv is the hardness for annealed 18k yellow, but
alloy A seems much harder than this to me.

the comfort fit bands using alloy A is a very successful
project.

i chose alloy C for a casting project. it is supposed to yield
harder results when only age hardening can be utilised. i cast
with a torch in air even though i was warned this could be
tricky. casting in air with induction or resistance melting is
reccommended. when i melted alloy C it developed a heavy dark
skin as soon as the metal started to slump that seemed to get
thicker the longer the alloy was melted. the sparks that fly
when one is burning off alloys (over heating metal) were evident
so i let the casting arm fly, hoping for the best. it was very
hard to tell if the charge was completely molten or not. i let
the flask cool without quenching. looking into the crucible there
was a small amount of the casting charge clinging to the walls
indicating the charge was not hot enough. once removed the
casting was a good fill but with a few cracks ( indicating that
the alloy was too hot, go figure)which were repaired with 21k
solder. the button was concave, indicating too hot metal.

i assume that the metal was too hot and the leftover metal in
the crucible was due to the less viscuous ‘skin’.

when discussing the cracks with the supplier he said it was
common when the metal went from too thick to too thin (from sprue
to model, 8g to 18g) and within the model ( which was a pierced
filligree ring about 1mm x 5mm).

one must use platinum type investments and crucibles.

i would deem the casting project with alloy C moderately
successful. the results were not as hard as the fabricated piece
with alloy C. nor was it without a few learning curve mistakes.
the finished jewelry piece was certainly acceptable, but not
pristine due to the repaired cracks.

when i am required to cast an object in either alloy i will be
certain be able to cast under vacuum or cover gas and without a
torch (or send it out to someone who does).

any process without melting is pretty straightforward and yields
great results.

the alloys are supplied in 8mm rods so one can roll them into
anything one desires.

the supplier : puregold, phone 510.262.0364. they were very
helpful and patient with my many phone calls and questions.

best regards,

geo fox

2

Hi George, This is really interesting. What were the burn-out
and the casting temperatures? I’m sure we all appreciate
like this. TIA.
Tom Arnold

3 
    pure gold is available in two options, both are .9985 pure
gold: alloy 'a' and alloy 'c'. alloy A is meant  for fabrication
and/or casting under vacuum. one can achieve greater hardness
with it than alloy C. --

G’day; I don’t understand how PURE gold can also be an ALLOY
at the same time. Surely a definition of an alloy is ‘A mixture
of two or more metals’ Also ‘to mix metals’ and also ‘to debase’

  • so how can it be pure?

Or is “Pure Gold” the name of the company which sells the stuff?
Sorry if I seem academic and awkward, but I really am curious.
Cheers,

        /\      John Burgess
       / /
      / /      Johnb@ts.co.nz
     / /__|\
    (_______)
4

I took it to mean that the company was called ‘Pure Gold’,
because the industry uses 4-9’s(.9999) for PURE gold. Wonder what
the .oo15 is- silicon, maybe zinc? What do you say, Geo Fox- do
you know? Or is it a trade secret? Ricky Low

5

hi Tom Arnold,

i’ll have to check on this info as it is written down
somewhere… while i’m at it there is also some info about
bright tinning high karat golds and using them for low temp
fusing…interesting stuff.

best regards,
geo fox

6

Hallo John, .9985 is not pure gold, because in 1000 grams of this
stuff there are still 15 grams of other substances in it. By
further refining it you can get a purity of .9999 or even .99999
but as you see it will never become in the strict mathematical
sense really pure.

Best regards
Hans-Joachim von Z=FCndt
@vonZuendt.allgemeine

7

hi john,

i would never cross words with that definition

yes it is and alloy called ‘pure gold’ distributed by a company
called ‘pure gold’. a micro alloy in fact. i think it is the same
company, mitsubishi(?) that brought us prescious metal clay that
manufactures this product. what exactly 'pure gold is alloyed
with is propietary. i did ask anyway and was told there are
amounts of galladnium and calcium in it.

best regards,

geo fox

8

Reading the posting, I’d say it’s an oddity, John. The words
pure gold implies truly pure, nothing else but gold, 100 percent,
etc. But in practice, chemically pure gold is not what we use,
nor the degree of fineness required to call gold 24K or pure
according to the law in most lands. Gold that is .9985 pure is
pure enough to call gold without specifying alloying agents.
And these folks seem to have found something to add to that gold
in only .0015 concentrations, that give it the desired working
qualities. So it is an alloy. But legally, it’s also “pure”.

Go figure…

Peter Rowe

9

george Fox… What is bright tinning? I get my gold from the
bank and it is always 9999 and couldn’t understand what they
were talking about with different numbers…But coloring really
intests me so would like to know more about this tinning and
blue gold… Thanks for any help… calgang