Subject: TRI-COLOR GOLD

From: [email-masked] (Allen Shechtman)
Date: Wed, 12 Jul 1995 22:22:55 GMT

Does anyone have any advice/assistance on alloy and solder mix to use
when attempting to attach strips of different colored gold together
side by side?
Assume there are 3 different colored strips each 1mm thick x 2CM wide
by 40CM long. The idea is to electronically arc the pieces together
into a 1mm x6CM x 40CM ribbon that can then be rolled thinner (and
wider and longer and eventually formed into tubing or made into other
items. It is critical therefore that the welds be smooth and seamless.
The problem is that the different colors of gold (and their alloys)
each have a different hardness, and when attempting to auto-braze, the
different hardnesses brazed together each require a different
temperature to cause them to fuse. This means that there is shifting
of the pieces as they get heated to the temperature needed to fuse the
hardest item, causing problems and movement in the softer  item
[similar to how a thermocouple thermometer works).
There must be something in my alloys, or there must be something else
that I can add or remove, to ensure that all various colors of gold
(R, W, Y) fuse at the same temperature. The problem is also that if
the gold becomes too hard due to additives, it also becomes brittle
and will not form into tubing or other items without cracking.
ANY SOLUTIONS, SOURCES, ASSISTANCE greatly appreciated.
Tnx
Allen Shechtman
FAX 416-740-3874
[email-masked]

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From: [email-masked] (Ken Christianson)
Date: 13 Jul 1995 22:43:56 GMT

In <[email-masked]> [email-masked] (Allen Shechtman)
>ANY SOLUTIONS, SOURCES, ASSISTANCE greatly appreciated.

----->  You might try the proceedure used by enamelers doing multiple
colors (each color melts at a different temperature).  Start your work
with the highest temperature required and complete all parts required
at that temperature.  Then move onto the next lower temp, and so on. 
At each step you can stop, cool and clean the part and then measure the
area required for the next pieces.  I would think that after doing a
few like this you will be able to eliminate the cool and clean steps as
you will have developed an understanding for the size compensation
required.
        Otherwise you might consider making a design change where the
gaps between the parts become integral to the overall character of the
piece.  Woodworkers will do this with woods that contract and expand at
greatly different rates by "rounding over" the edges near the joints
which gives them a more pleasing transition that does not appear so
abrupt.
        Finally, remember that as artificers in metal, we never make
mistakes - we only "create design element opportunities" !

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From: [email-masked] (ErnieLeim)
Date: 15 Jul 1995 02:14:35 -0400

The solution to your problem is a process called mokume gane.
The process has been well documented and Bill Fiorini of the Univ. of Wis.
at Lacrosse art school has done some wonderful work with gold and copper
alloys.
The process involves heating a sandwich of several alloys in a controlled
atmosphere furnace while clamped between steel bolt plates.
The pieces have to be extremely clean and flat .
At a specific temp. the pieces actually diffusion weld together and can be
removed from the furnace and hammered together. Once the hot bolts are
sheared off the billet is reduced by 75% in thickness to complete the bond
. it gives a beautifully clean lamination effect.
Most people do it with copper and silver alloys but some have done it with
gold .
I seem to remember a set of wedding bands by Bill Fiorini that had 4
colors of gold twisting through them.
Talk about gorgeous.
I believe there are several books that cover the process.
Good luck.

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