I have been researching the topic of mokume gane for over a year now
and have found many useful sources threw the many books and videos I
have purchased and threw the helpful advice of everyone here at
Ganoskin. Threw my struggles I have been able to find almost
everything I need to create my own billets. The only thing I am
lacking is the particular metal shakudo. I know that it is a Japanese
alloy of gold and copper (Seven percent gold to copper most of the
time at least that seems the most common?). Unfortunately I have only
been able to come up with one source for it being Reactive Metals.
While I am sure there quality is great I still believe that I can
probably make it on my own (and for a lot cheaper than they want).
The exact method of doing this is where I run into a wall. Should I
just combine 7 percent gold to however much copper I use and just
melt it together in a ceramic crucible with an oxygen propane torch?
Due I use fine gold or another karat? I was told that I should use a
graphite crucible to melt it in and if so do I melt the alloy in a
burn out oven or do I use a torch and coat the liquid metal with
borax or another material to prevent adding to much oxygen into the
mixture? From there do I just pour it into my ingot mold and start to
roll it out flat, or should I use the Japanese technique of pouring
it into a cheese cloth submerged under water. Any helpful advice on
the alloying, mixing and or forging of the material will be much
appreciated.
I am no expert on metallurgy or Mokume Gane - but I have worked with
it some. I alloyed my own Shakudo and it turned out fine - I used a
standard porcelain crucible and an oxy-acetelyene torch, I’m sure
oxy-propane would be fine. I used a 22k or 24k? gold maple leaf
coin. The advice given to me, and it seemed to work, was to partially
melt the copper - until it resembled the texture of a slushie when
stirred with a carbon rod - and then pop in the gold coin (Copper has
a higher melting temperature than gold) and continue the melt,
stirring once more to be sure the metals are mixed. Flux with borax
as per usual when casting an ingot and be extra careful to keep your
torch over the melt the whole time to reduce oxidization. Pour when
the surface of the molten metal is shimmering and glassy but don’t
overheat. Forge the ingot lightly before rolling.
In terms of patination - I achieved the classic blue-black colour by
fuming with ammonia.
I have made shakudo similar to what you want to do. It’s easiest to
use fine gold because the formula is soo much easier to figure. Using
karat gold you have to calculate how much of the alloy is not gold
and add it to the copper allotment (assuming the rest is copper which
it probably is not). I melted it in a ceramic crucible and made sure
to stir the melted metal with a carbon rod. Use borax as a flux for
melting. An oxygen propane torch should be fine. I poured mine into a
standard ingot mold. The alloy rolls out fine. If you prefer the
Japanese technique, use it, whatever you’re comfortable with. The
metal doesn’t care, you do.
We have made shakudo for folks before. We just made grain for them
to cast. The tricks are use really pure copper and of course gold,
and keep the oxygen out of the metal with good flame or atmosphere
control. We used hydrogen oxygen, I would think propane oxygen would
work just as well. Foremost-Do not use dirty tarnished copper.
We do not make wire or sheet out of shakudo.
Go for it. I think you are right about being able to do this
yourself.
When I was producing shakudo I used fine gold to mix with the copper
in a ceramic crucible using a torch. I also produced my ingot using
the traditional method of pouring onto a cheese cloth submerged under
water. You seem to understand the need to prevent the shakudo from
absorbing O2 when alloying and pouring the ingot and this is also
equally important when making the mokume gane. My understanding is
that traditionally the heat source would have been a coal fired forge
or oven which would provide a natural reduction atmosphere, so
anything you can do to provide as much of a reduction atmosphere as
possible will improve the quality of your sheet. Use a reduction
flame, lots of flux should help and I threw some small wood chips on
the surface during the heating stages of the alloy and just before
pouring the ingot to reduce the presence of O2.
I was always amazed at producing a beautiful ingot by pouring into
water and never even scorching the cheese cloth. Hope this helps.
Here’s a question for you alloying specialists! I was attempting to
alloy both 4% and 7% shakudo using a Kerr electromelt furnace. I was
producing only 2 oz of each, so yes, the furnace was definitely
overkill. My problem is that when I tried a number of patinas on my
samples, the 4% consistently patinaed darker than the 7%. I believe
my math in calculating the percentages of gold were correct (there
was certainly more gold in the 7% at any rate) and I used a very
sensitive balance in weighing my metals. I first alloyed the 4% and
then alloyed the 7% using the same crucible. When I made the 7%, I
forgot to add the gold, so I cleaned and remelted the copper ingot
and then added the gold. I was distracted from what I was doing, and
when I went to pour the 7%, I noticed that the alloy was boiling.
Can gold boil out of the solution and that is why I am seeing what
appears to be a lower percentage alloy? Any help would be much
appreciated. I am a student, and have been afraid to use the gold
(my first) for two years now because it is sooo expensive. Then I go
dumping it into copper!!! Go figure.
I noticed ‘same crucible’. in your post that i quickly skimmed…
therein lies the proverbial rub…use different crucibles for
different metals…always mark what’s in them and clean and recoat
with flux when colored oxides build up in the glassy spent flux. A
remedy you can also try to use: combine sal ammoniac and charcoal
powder ( sal ammoniac is available at stained glass supply stores in
a handy cube really cheap) to purify the alloy, air cool, then remelt
in a cleaned and relined or simply different (if not open torch
method) crucible and then use regular flux( borax/and a bit of salt
petre for Au and just borax +boric acid for Ag) while remelting and
pouring the ingot that may clean it well enough to yield a nice
bright ingot that will anneal and roll smoothly.
Possibly use a digital scale (particularly as you get older and eyes
go as opposed to an assayists scale) and write everything down so
you can trace your steps when beginning to alloy with expensive
precious metals. I mark open melt crucibles, graphite or
composite/clay bound or fused silica with an heat proof / ultra-high
temp conductive silver paint pen as is available at some electronics
dealers (radio shack for example- the same pen is great for primitive
electroforming ! ), or simply notch rather shallow marks in the
crucible’s bottoms to denote the dedicated metal that each will hold.
I have managed to save that first ingot of gold I ever poured and
learned basically the same lesson on mixing crucibles, or rather not
to, with. It is a fascination that stirred me to alloying as one of
the many passions involved with jewelry making…
There is a book I highly recommend by Harold O’Connor, entitled, “the
Jeweler’s Bench Reference”. though out-of-print it is still fairly
widely available for under twenty dollars and is almost invaluable
in the shop for those calculations, formulas, and measuring devices
among other things that we tend to forget without a handy reference,
in a handy format- which is what this little high mil black vinyl
covered spiral bound book is. You should get one. ( if you want one
but can’t find it conveniently, write me off Orchid and I can help).
As for the gold boiling out of solution i’m not certain what you
mean, but i have only lost gold in aqua regia solution not a melting
furnace, muffle, or crucible- although i used to come up with some
strange tough alloys that i attributed to contamination by steel
bits from saw blades or files, etc, in scrap reclaimation once upon a
time, until i discovered the ease of magnetism in removing those
micro-bits from my sweeps and scraps and filings.
…and an aside to those of you who dislike my arcane uses of chemical
terminology…too bad! that’s what I know, that’s what I call them,
that’s what I look for in off- the- beaten --path --stores ( and
probably why I pay a lot less than most for items -because many don’t
recognize that the quarter pound $1. 35 sal ammoniac block in a
stained glass supply store used for cleaning and tinning a soldering
iron is the same sal ammoniac, or Ammonium Chloride/ NH4Cl used for
centuries by goldsmiths for purifying metals and alloys and sold as
Ammonium Chloride at a much higher price, per oz., by large supply
houses that many jewelers and hobbyist metalsmiths rely on)…and I
don’t intend to rethink how I phrase my chemical terminology for the
sole purpose of posting on Orchid at this point in my life, -
alchemy and archaic woodcuts of ‘the jewelers shop’ c. 1300’s is what
attracted me to jewelry making in the first place, thank you…