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Gold alloys


#1

Hi again,

I’ve been doing some research into different colours of gold
alloys. I’ve been trying to discover more info on the bluish gold
(75% gold, 25% pure iron) but I haven’t been able to find one peep.
I have a few questions to pose regarding this specific alloy, if
no one minds terribly: 1. What sort of pickle would one use with
this? 2. Would it eventually rust or something? 3. Is it easily
alloyable with just a plain crucible, propane/oxy torch and normal
ingot mold? 4. Is it a brittle gold: can I easily bend it or bang
it? 5. Is it safe to run through the rolling mill and to use with
normal tools? 6. Does it have a high enough final melting temp to
withstand soldering with 18K white solder? 7. Am I totally nuts
here in wanting to try it? Is there just too darn much involved in
the experimentation?

Anyhow, I thankyou all for your patience and your wisdom. You are
all a truly helpful bunch!

Tobey Robinson
Adoremus Creations in Metal
Burnaby, BC, Canada
ICQ: 2643004


#2

Tobey, The blue gold i have seen comes out of Italy and is a
patented process. It is brittle and will not roll or bend and is
always mechanically attached as it will take no heat .heat will
cause a change in color. I have heard that is is alloyed with
aluminum to produce the blue color although i could be wrong in
this. The blue color is the result of twenty years of research and
developement by an italian goldsmith, or at least that is the story
i was told by the people selling the jewelry line with blue gold in
it. Who knows truth from hipe! luck with your search for the ever
elusive blue! Frank Houston, tx.


#3

Tobey:

AURUM 34 has two articles about blue gold…one is about Vittorio
Antogniazzi’s and the other about mine that I was doing for Harry
Winston since the early '80’s. There have been references to
blue golds in some french smithing books since the 1850’s.

It does require a lot of experimentation. The real problem with
people asking for answers to esoteric is:

  1. If someone busted their ass doing research for their art, (
    unless they’re dying, or academicians) they have invested serious
    personal value(blood and sweat and money and time), and they want
    to eat the fruits from their garden. And the truth is that ( if you
    ever spent many years to defeat a demon), they deserve that fruit.

  2. If it were easy, even with a step-by-step manual…anybody
    could do it. Value lost.

If you spent 5 years in my shop, maybe I could show you the ins
and outs of SPA’s (special patinatable alloys). It might sound
rather coarse, but if you want to be an explorer, you’re on your
own…you’ve got to take your own risks. It doesn’t come easy, and
if it does, you’re only re-treading someone elses footsteps.

THE QUESTION IS: WHY DO YOU WANT TO KNOW?
There are many ways to create the color blue on gold, Paint,
nickel-plate, ion bombardment, chemical treatments, intermetallic
compounds, stone inlay, oxidation, enamels, etc. Those who have
been working with blues (me, Patek, VA oro Azurro, Franco in
Bologna, L. Mueller), are not telling.

It’s one thing to create and alloy and form it, cast it , etc,
another to master it. Are you ready? Then, as we say in the US,
“go for it”. Some mediocre types, brush lightly on a technology,
create small samples and then publish in order to “plant their
flags” on something they only understand superficially. Isn’t it
battle to find out and discover, is why you want to know, Tobey?
Or do you want it handed to you? How are we going to move
forward, People!!! Faites vos jeux…

Steven Kretchmer


#4

Hi group,

I couldn’t agree more with Steven Kretchmer. The need for instant
gratification and to have everything handed to oneself has led to
more problems than not in society. Credit so we can have it now
and pay for it later is the prime exemple of this. Others still
blaming the wealthy for having too much money that they worked hard
for and earned.

Listen, there is a wealth of out there in books and
even on the internet. Go forth, research, and discover something
new instead of worrying about what someone else has already
discovered. You may want to learn to make blue gold to use in your
own designs, but what if instead you spent your energy
experimenting and dicovered a malleable purple gold alloy?! Even
by accident this would be a great accomplishment. There is so much
more to be dicovered and invented yet than there has been so far.

Good luck, and good hunting,

Chris Maugham
JA-CMBJ


#5

Hello, I am Bart Bourgois and just one week on the net and find
already ganoksin. I hope that my connection was right, if not
please help me.

I already have a question . Can somebody give me the best alloys
for gold 18 kt ( yellow-white-rose) to make hand-made
jewellery.Thanks in advance.


#6

18k gold alloys you can mix yourself:

There is a virtual metalcopia of possibilities for 18k alloys.
The most co mmon 18k yellow is 750 parts Au, 125 Cu and 125 Ag,
deep red is 750 Au with 250 (or close to it) in Cu and perhaps a
dash of Ag for hardness. White is more complicated because many
metals can be added, depending on the specific application.
Standard 18k white is 750 Au, with 110 in Cu and Zn plus 140 Ni.
This is a hard alloy (220 Vickers when annealed, 350 when
worked!), not id eal for setting, forging or forming. However a
much more workable (and more costly) 18k white is 750 Au, 105 Ag,
35 Cu, 1 Zn, 9 Ni and 100 Pd. It has a hardness of 95 Vickers
when annealed and is also called setter’s white gol d because of
its preference by those who set bezels, prongs and bead.

I suggest you refer to page 206 of my book, Professional
Goldsmithing. I compiled data from a variety of sources to create
a chart of 14k and 18k alloys. They are listed by color (shades
of green, yellow, rose, red and white) and composition, as well
as the corresponding density, solidus, liquidus, hardness
annealed, worked and heat treated, plus tensile strength, yield
strength and elongation. The best part of the chart is the
recipe fo r heat treating (age hardening) these alloys. For
instance, 14k yellow which is 585 Au, 205 Ag and 210 Cu has a
hardness of 190 Vickers when annealed. If you work it, you can
reach 260 Vickers. But what if you want to make a soldere d money
clip that requires a springy alloy or what if you want to harden
a w ire that has been soldered? The head of soldering takes out
the hardness and anneals the metal, leaving it in a soft
condition. However if you take the piece of jewelry and put it
into an oven set at 360B0C for 60 minutes, th e hardness increases
from 190 to 270 Vickers, even harder than if you had hammered or
rolled it! That’s a useful bit of to file away for
when you need to harden some metal after it has been soldered.
Alan Revere


#7
   There is a virtual metalcopia of possibilities for 18k
alloys. The most co mmon 18k yellow is 750 parts Au, 125 Cu and
125 Ag, deep red is 750 Au with 250 (or close to it) in Cu and
perhaps a dash of Ag for hardness. 

Good info, Alan.

But I’d offer just a short caution with regard to an 18K red
gold with 750 Au and 250 Cu. That alloy, when slowly cooled from
casting or annealing temps forms, at (if I recall right) about
750 degrees, a structured laminated atomic structure rather than
the normal random mix of copper and gold. If you happen to have
a copper/gold phase diagram handy somewhere, this structured
phase is found over on the right side as a weird small little
vertical parabolic curve sort of in the middle of everything, not
connected anywhere. At this formula, despite the gold being 75%
by weight, it’s about a 1:1 ratio of copper to gold atoms, and
they like to form this unusual structured array. Unfortunately,
this array structure is very brittle, almost reminiscent of the
intermetallic compounds formed by gold and aluminum. So a slowly
cooled 18K red gold can easily become prone to cracking, often
microscopic ones, which do not heal un subsequent anneals. To
avoid this problem, this alloy MUST be quench cooled from just
below red heat when soldering or annealing, and not allowed to
air cool. The same goes with casting this alloy, the flask must
be quenched pretty hot, to avoid this crackiness, rather contrary
to intuition, which might lead one to think (correctly with some
other alloys) that too hot a quench would cause cracks. This
behavior can be quite problematic with some constructions, where
avoiding this slow cooling in smaller parts during a complex
assembly or the like, can be quite difficult.

The answer, of course, is to add sufficient silver to mess up
this behavior. In my experience, adding silver to a copper/gold
mix doesn’t increase the hardness much. The rose golds are
already pretty hard. But the silver will increase the strength
and durability of the item, by solving this cracky behavior that
the straight copper/gold 18K is prone to. Again, referring to
that copper/gold phase diagram, use enough silver so the copper
percentage now falls outside of that little bell shaped curve.
Doesn’t take much. I usually use about 1 part silver to 10 parts
copper as the alloy to add to the gold. Lightens up the red
color on very slightly.

Peter Rowe


#8

Peter, Wish I had seen your post a year ago on 18K red gold.
After three attempts at casting and calls to supplier I was
unable to produce a rush job wedding ring in 18k red without
cracks. I think I’ll try it again now. Steve Howard


#9

hi! everybody

i wish to know that how many grams of 24 karats of gold is required
to make 10 grams of 22kt gold, 20kt and 18kt gold and what are the
alloys required and in what percentage. and also how to test the
purity of the gold please reply as soon as possible

regards
ankita gupta


#10

Hi ankita,

How much pure gold in 10 grams of alloy:

22k   = 91.7% Au   = 9.17grams
20k   = 83.5% Au   = 8.35grams
18k   = 75.0% Au   = 7.50grams

Regarding the other components, they affect the gold colour. What
colour gold do you want? For a yellow, try a 1:1 ratio of
silver/copper:

alloy     Au       Ag      Cu
22k      91.7%    4.15%    4.15%  
20k      83.5%    8.25%    8.25% 
18k      75.0%   12.50%   12.50%    

alloy     Au       Ag      Cu      Total
22k      9.17g    .415g   .415g    10grams
20k      8.35g    .825g   .825g    10grams
18k      7.50g   1.25g   1.25g     10grams    

Hope this helps.

Bri
B r i a n � A d a m
http://www.adam.co.nz/


#11

Ankita Gupta - Divide the karat of gold that you want to achieve by
24(pure gold). This will give you the percentage of gold that you
need. Multiply the total weight you need by the percentage and you
will have the amount of gold necessary. 22k gold is 91.67 percent
gold and 8.33 percent alloy. 20k gold is 83.33 percent gold and 16.67
percent alloy. 18k gold is 75 percent gold and 25 percent alloy.
The specific makeup of the alloy would depend on what color you want
to end up with. Various alloys ready for melting are available from
metal refiners. Just add the appropriate amount of alloy to your pure
gold. Hoover and Strong (http://www.hooverandstrong.com) carries a
full range of alloys.

Steve.

Steven Brixner - Jewelry Designer - San Diego CA USA
mailto:@Steven_Brixner4
http://www.brixnerdesign.com