I was wondering…? why is it that sometimes when I anneal
yellow gold rather than annealing, I wind up with a brittle and
often broken piece of wire? I’m sure that at some point I knew
the answer, but I can’t remember what I’m doing wrong… too long
or too short at temperature?..too hot, too cool?..to quick or
slow to quench? It drives me crazy when it happens (especially
three days before Mother’s Day). Can someone tell me what I’m
doing wrong and give my feeble mind a break!
Thanks in advance.
Sharon Ziemek
Perhaps you overheated the wire and it absorbed too much oxygen.
My guess would be too hot. Nickel white alloys souldn’t be
quenched, they harden.
Rick Hamilton
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why is it that sometimes when I anneal yellow gold rather than
annealing, I >wind up with a brittle and often broken piece of wire?
Hi Sharon, Some yars ago, the WGC issued a magazine called
“aurum”. There was a series of gold alloy data sheets, where for
annealing a temperature of 550 Centigrade for half an hour after
a 75%min transforming of the material was recommended for all
the yellow (and rose) gold alloys, with immediate quenching
afterwards. As most of us do annealing with the torch, I presume,
these parameters are hard to observe. The problem is, the higher
the temperature and the longer the annealing takes, the larger
the cristallites in the metal grow. Working any metal, precious
or steel, you opt for as small as possible irregular
cristallites (“grain”), as this gives the best basis for
transformation. Because you can “split” and shift a cristal only
along certain planes and directions (similar to the cleaving
planes in gemstones - hope to use the proper English term), the
more cristals you have, the more options for transforming. So
much for theory. Annealing with the torch, you should have worked
the metal at least 75% for yellow gold alloys, that is a 3 mm
wire drawn down to 1.5 mm - that is right, the 75% are for the
area of the cross section. Then warm up to a dark red heat,
hold for a minute and quench immediately. Thas worked for me,
hope I didn’t bore you, Markus
why is it that sometimes when I anneal yellow gold rather than
annealing, I wind up with a brittle and often broken piece of
wire
Sounds like you are heating almost to the point of melting, it
shouldn’t “sweat”. Or maybe you have super human strength. The
only time that happens to me is when I get it too hot. Or your
using old contaminated material. Could be that super strength
thing.
Mark P.
hi sharon, there are as many answers to your question an ther
anealers.
what i do is turn off overhead bench lighting and gently heat
the coiled wire to a dull red. use a reducing flame (with a tiny
bit of yellow at the inner cone, nice and brushy) let the metal
cool quite a bit. i usually will spit on my finger and if it
sizzles when i touch the metal (quickly) it’s too hot.
it sounds like you have either over annealed (too hot, too
red)or had too much oxy in your flame or you could have quenched
it too quickly. don’t quench directly in acid.
i also will heat the metal on a charcoal for yellow gold with a
screen under it. i use a solderite board for white. white
doesn’t seem to like charcoal. it always cracks if i heat white
on charcoal.
hope this helps.
george fox
Sharon Ziemek
I was wondering…? why is it that sometimes when I anneal yellow
gold rather than annealing, I wind up with a brittle and often
broken piece of wire?
Hi Sharon, One point you might want to keep in mind is if you
are working from a square ingot, and rolling down and then
drawing your wire is that you have to roll and draw from the same
direction each time. If you dont, then the crystal structure of
the gold will compress in different directions. Also, you want to
make sure you are heating the wire uniformly, to avoid creating
different grain sizes and hardnesses in the metal. If you dont
anneal for a long enough period of time or at a high enough
temperature, you will get no change in the size of the grain
structure. If you overheat it, then you will get too large of
grain size. Overheating and underheating can both result in
brittleness and a decrease in malleability and ductility. Here
is a formula that works well for me: Work harden the piece to at
least 50% (in the same direction) Anneal at 1250F in an oven for
30 minutes Quench the piece(yellow gold only) immediately. White
gold quench after all reddness has dissapeared. If any cracks
appear, fix them immediately by either grinding them off or
welding them. After annealing, use a scotchbrite pad to remove
any residual oxides, then re workharden in the same direction
again.
Thanks to all who gave me info on the annealing process!
I realized that I have been slowly drifting upward with my
annealing temperature over the last few months until I finally
had problems. You all have me back on track again.
Thanks.
Sharon