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Properties of Purple Gold


#1

Hi,

Can someone tell me about the Purple gold? I heard that it very
brittle

Pl. share your experience with it.

Thanks
Dinesh


#2
Can someone tell me about the Purple gold? I heard that it very
Brittle 

AU Enterprises, in Berkley, Michigan, casts this material. I’m sure
they’d be happy to tell you all about it. Their number is
800.637.CAST. I saw a piece of 18K purple at their booth at the Bench
Jewelers Conference last month, and I can attest to it being REALLY
purple. It is also very brittle. The piece they had on display had
broken in half after being dropped into a lap tray from the benchpin.
As I recall, I was told that it is an alloy of 25% aluminum/75% gold.

Matthew Crawford
www.MatthewDesigns.com


#3

Dear Dinesh,

I did a research paper on gold alloys during my undergraduate
studies at Northern IL Univ. It was 20 years ago, but I remember the
purple gold experiment with detail.

Purple gold is an alloy of 24k gold and pure aluminum. The color was
a light grayish-purple. To get the aluminum to stay molten with out
evaporating I had to melt it in an Argon atmosphere. Once I got the
two metals to alloy the resulting ingot was un-millable. It cracked
and fell apart under the slightest pressure in the rolling mill.
Hammering it only sent shards of the alloy splintering everywhere.

There was an Italian line of jewelry featuring it commercially about
10 years ago and they where bezel setting cast pieces of it like

Nanz Aalund
Associate Editor / Art Jewelry magazine
21027 Crossroads Circle / Waukesha WI 53187-1612
262.796.8776 ext.228


#4

hi i’m sort of the expert on AuAl at the moment…untill someone
deflates my ego that is… i have been waiting for my patent to
arrive any day…no really, it has been awarded, recorded, but just
not recieved yet…

It is an alloy of aluminum and gold.As you know Al melts at a low
temp, Au at a higher temperature, the trick is in the buffering and
method of casting…it was invented, or rather stumbled upon in the
10th century hence there was no gas covered casting machines with
vacum’s attached for good measure back then so the question was
figuring out what would make the compound less brittle, while
maintaining the richer than lavender hue that it takes on, and in
some cases, a dense positively red-violet colour is obtained, in
which the blue can only go a few degrees into the blue spectrum from
there…what most modern casting companies produce is a brittle,
inlaying type material, that can be milled flat, or into a fairly
thin rectangular wire, round wire doesn’t suit it’s micro-crystalline
structure…or something like that, in my experience…making the stuff
ductile is the secret, and making it not look like a shriveled
peppercorn when direct cast is also an entirely possible outcome. I
hate to reveal the secret of producing the material…because it cost
me about 6,00.00 total to come up with the formulae, trials,
controls, etc…to get a consistently malleable, and sufficiently
ductile product that can be rolled, milled, hammered,
cast,copyrighted, etc, and about two years of fairly solid work…to
get that consistency… so my advice is this…think of the substances
that were readily available during that period of time, think simply,
make sure you use a stripping strength pickle to remove suface oils,
dirt, etc from the gold, and a good rinseable degreaser from the
aluminum. use a new crucible dedicated to the compound, and try to
pour it into a charcoal block if that is a possibility for you,
rather than a metal mould ( thermal shock- when two metals are so far
apart in melting temp. are a key here…Also consider the charcoal
block…and what you think is necessary in its immediate environmnet
to give the best most bonded alloy…it’s an easier puzzle than you’d
think…I hope to make a little money off of selling the method to one
of the more conscious producers of gold raw materials and jewelers
stock out there…so if you have some specific questions i’ll be
happy to answer. Don’t be put off by the experts that will respond
and tell you it can’t be done without thousands of dollars worth of
tools and supplies, or that you’ll come up with a mass of inlay-able
bits that are so brittle they’llbreak like schist from handling
them…i’ve done it, i’ve had consistently fluid-;ike results ( as
opposed to brittle - in a semantic sense of fluid-like_…) and keep
refining your inquisitive and curious nature…it’s good for you…

R.E. Roark, goldsmith etc…


#5

Please would you share a picture of a piece that you produced with
your alloy?

Cheers
Matthias


#6

Dear Nanz.

Thanks for the Email.

So the result “Do i consider it to be unworkable” as of now for my
casting and finding application?

Regards,
Dinesh


#7

In a search of the USPTO data base that is current to May 16 2006
there is only one patent naming purple gold in its abstract and it
is the one out of Singapore by Peng Chum Loh. When did you get your
patent? and where? As you no doubt know patents are public domain
documents once granted your protection is by law rather than from
keeping it a secret. So how do you cast ductile purple gold?

James Binnion
@James_Binnion
James Binnion Metal Arts


#8

I could be mistaken, but my understanding was that Steven Kretchmer
(of tension-set diamond fame) was the inventor of a purple gold
alloy. If someone knows more, please let me know.

Leslie
HOS


#9

Ms Roark,

I have a patent barrister/venture capitalist that I've been working
with for about three years on this one process that has intrigued
me for many years..I have been told it is to be awarded, and
recorded and within 6-8 weeks i should be holding it in my hand, at
which time L.Drogs has, i believe, agreed to help me decide what to
do with it other than just hold an NDA type patent......the thing
that really gets me is you "professional goldsmiths" saying i have
not done it, it can't be done, and basically refuting my research,
and in a sense wanting me/ demanding that i reveal how i make the
alloy ductile and what i call "splatter-proof"..yeah, public info
is public info, there are also caveats about non-disclosure that
any good counselor in a given location can invoke that protects my
process, (which is actually not really -mine- because it was done
in the early middle ages apparently- and without argon gas) from
people like you that would apparently sell it tomorrow 

I did not say you haven’t done it, but your post is like many that
claim some special knowledge that flies in the face of what seems to
be reason. Aluminum was not isolated as a metallic substance until
the early 1800s so how can monks in the 10th century have used it to
make purple colored gold alloys? Also AuAl3 ia an intermetallic (one
property of which is that it is brittle) so, if you have done this
then congratulations. But I am hope you can understand my curosity
and skepticism as to how it can be possible. I did not attack you
personally like you have attacked me in your email I just asked you
to share with us a contents of a public domain document. Your
suggestion that I would steal your intellectual property is highly
offensive. Yours is hardly the kind of behavior that one would expect
from someone who claims to enjoy sharing your knowledge as you do in
your email.

James Binnion
@James_Binnion
James Binnion Metal Arts


#10
I could be mistaken, but my understanding was that Steven Kretchmer
(of tension-set diamond fame) was the inventor of a purple gold
alloy. If someone knows more, please let me know. 

I was given a list of gold recipes about 15 years ago, for about any
color imaginable, including purple. I don’t know how long Mr.
Kretchmer has been making it, but I do know that the jeweler who gave
me this list had been using it for many years before I weaseled a
copy of it from him.

Matthew Crawford
www.MatthewDesigns.com


#11

After a little more searching there are several patents in the world
patent search engine at the European Patent Office

http://tinyurl.com/a5x64

that are for purple gold. But only a few that are called a “workable"
material one is JP62240729 it is a sintered (powder metal) alloy of
AuAl2 and Cr, Ni and Pd that is fused together and the inventor says
"The resulting sintered gold alloy has satisfactory workability and
an original hard fine purple color”. Another is JP61030642 But they
must not be too workable or may be too expensive to produce as the
patents were issued 10-20 years ago and don’t seem to have entered
the market. All the others were some form of diffusion of an aluminum
coating into a gold substrate to in effect plate the substrate with a
purple layer like a patina or electroplated coating.

Jim

James Binnion
@James_Binnion
James Binnion Metal Arts


360-756-6550


#12

Hey Matt…

the jeweler who gave me this list had been using it for many years
before I weaseled a copy of it from him.

Sooooo…How do we weasel a copy of that list out of you??

:slight_smile: :slight_smile: :slight_smile: :wink:

Lisa, (Twisted my ankle today. Ow!), Topanga, CA USA


#13

Well, there was good purple gold in 1945, Ivan Landstrom was using
it.

Mike Rock


#14
Also AuAl3 ia an intermetallic 

Sorry typo, it should be AuAl2

James Binnion
@James_Binnion
James Binnion Metal Arts


#15

Jim,

At the U of Wisc., Dave Mack, prof. had a crystal of AlAu, I believe
tha Al2Au alloy mentioned. BRILLIANT purple fracture surface,
unworkable. It is an intermetallic. Man, it was beautiful.


#16

Hi Mike,

At the U of Wisc., Dave Mack, prof. had a crystal of AlAu, I
believe tha Al2Au alloy mentioned. BRILLIANT purple fracture
surface, unworkable. It is an intermetallic. Man, it was beautiful. 

AuAl2 is the most beautiful purple it is almost “electric”, very
intense. I love it, it is just that it is so brittle and all the
attempts to date to make it “workable” that I have seen cause it to
lose that very vibrant intense color. And none of then are what I
would consider workable just not so brittle.

Jim

James Binnion
@James_Binnion
James Binnion Metal Arts


#17
AuAl2 is the most beautiful purple it is almost "electric", very
intense.

This might be too “out of the box” but has anybody tried to facet
this substance? I mean not expect it to work like a metal but more
like a mineral?

Curiously yours,
Betsy


#18
This might be too "out of the box" but has anybody tried to facet
this substance? I mean not expect it to work like a metal but more
like a mineral?

Even my Idea behind using purple gold is to do Faceting the casted
plate with a High speed diamond tool. Can this work?


#19

Has anyone tried to sputter a layer of aluminum on and then diffusing
it into the surface ala semiconducter techniques??

jesse


#20
Has anyone tried to sputter a layer of aluminum on and then
diffusing it into the surface ala semiconducter techniques?? 

Yes that is the basis for at least one of the Japanese patents.

James Binnion
@James_Binnion
James Binnion Metal Arts