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Brittle Gold


#1

Had a new one yesterday. An elderly woman came in needing a repair
on a 50 year old 14ky Art Carved wedding banch she said had never
been off her finger before.

The band was out of round a good bit, and the “break” was a place
where the metal was stress cracking. No solder joints.

Once I got it off and tried to round it out I realized that the
entire ring was either some kind of spring alloy, or incredibly work
hardened after the years of flexing on the finger.

We tried annealing it but no change in the structure. So we cut at
the tear, flushed the ends, and then attempted to move the two ends
together - at that point cracks appeared in two other places.

Once we got it lined up, we attempted to hard solder the joint, but
right at the solder flow point, the body metal began to collapse as
well.

Short ending: we repaired all three cracked areas - including the
original - with medium solder. But the question is, was it just work
hardening and stress cracking, or was there an alloy issue as well?

Any thoughts or ideas?

Les Brown
L.F.Brown Goldwork, Inc.
Kallispell, MT


#2

speaking of brittle gold, I have had a couple hollow rope chains,
that were so brittle you could crumble the gold with your fingers,
and harringbone chains that crumble easily also. just figured body
ph?? Rick


#3

Les, I wonder if she swims or if the water where she lives is heavily
chlorinated. Sounds almost like something is deteriorating the
gold, and long-term or intense chlorine exposure (i.e., water
exercise on a regular basis or showering/baths daily) could possibly
account for what you’re seeing. Just a thought, may be way off base.

Good luck,
Karen Goeller
@Karen_Goeller


#4
Short ending:  we repaired all three cracked areas - including the
original - with medium solder.  But the question is, was it just
work hardening and stress cracking, or was there an alloy issue as
well? 

Dear Les, It makes me wonder if this lady had been a nurse during the
50 years that the ring had been on her finger. I have seen things
that resemble what you described after a ring has been exposed to
mercury. When a gold alloy is exposed to mercury, the mercury tends
to migrate deep into the metal. The normal way to repair this is to
heat the entire ring above the vapor temperature of mercury under
"extreme" ventialtion. If it has been exposed and a repair had been
attempted heating the ring until the mercury had “boiled” off then
the surface could appear yellow once more. The inside however could
still be an amalgam. Residual mercury can make the ring brittle as
well as can age or case hardening. The part that you described as
"the body metal began to collapse as well.", would either make me
think that 1. you were using too hot and too small of a flame (which
I doubt), 2. The solder you were using had a higher melting
temperature than the original band alloy, or 3. the metal contained a
contaminant that greatly altered the liquidous temperature of the
alloy. Mercury tends to make an alloy mushy and under the stress
conditions of “flushing up the ends”, it might appear to collapse.
Interesting.

Best Regards,
J. Tyler Teague
JETT Research


#5

It has been a long time since I have had that problem, but that may
be just because there are so few people still wearing rings that old.
LOL. I think it is an alloy issue. When I have run into these
problems, I also have noted that those rings, when used as scrap
material, do not melt and roll out nicely. Can’t seem to anneal
right, very brittle no matter what I have done to them. If those
have been presented as scrap, they just go on to the refinery.
Unfortunately, I don’t have any idea what the alloy materials are in
these oldies. Jim


#6
      I have had gold that was cast with acetylene behave that way
--- 

Also - I am a LONG time lap swimmer (several days a week x 30 + yrs)
and my own jewelry that has been exposed to chlorine has never
behaved that way.

Linda Weiss
www.lindaweiss.com


#7

Dear Les A gold alloy containing small parts of tin (Sn) becomes very
brittle and if the tin is a major part of the alloy it also would
reduce the melting point considerably and could reach a point way
under the melting point of a medium solder. Regards from Bornholm,
Denmark, where the weather is behaving like spring Niels


#8
    Also - I am a LONG time lap swimmer (several days a week x 30
+ yrs) and my own jewelry that has been exposed to chlorine has
never behaved that way. 

Linda, It is a confirmed fact that chlorine attacks the alloys in
precious metals, not necessarily the precious metal itself. And the
nickel in white gold being the most affected. I had a customer SOAK
her jewelry in Clorox bleach, the result was metal that looked like a
sponge! The precious metal was there, but the alloys hade dissolved.
You could crush ring shank with your hands! All her jewelry had to be
remade. Thomas Blair