So a client and I have melted down almost an ounce of mostly 14K
yellow and some mystery gold. We are rolling it into a chunky sheet
that we will bend into a band ring.
I am used to doing this process in 18 or 22K gold, but not in 14K.
We are constantly battling cracks, and the piece is very hard. We are
annealing to a red, letting it cool a couple of seconds then we
quench, pickle, sand and roll through the mill. It gets 2 passes
through the same tightness before we clamp down even tighter,
although only a tiny bit more tight. Sometimes we do a fusing like
process over the cracks during the annealing process where we heat
them up very hot to fuse a little, and then we ball peen hammer over
the cracks. Sometimes we use a belt sander to sand below them.
I worry that when we go to bend this piece into a ring it will just
crack all together. We are going to bend it on the kick press. Would
anyone recommend working the gold while it is still hot? Does anyone
have any more suggestions on how to do this more safely. We are
almost to the point of bending and soldering. Any tips on this would
be greatly appreciated.
I’m betting its your “mystery gold”. Remember that there are 2 basic
kinds of gold alloy. One is a rolling alloy, which will roll out
well, and designed for that purpose. You can also cast with it. The
second type is a casting alloy. It casts well, but will NOT roll out
well at all. In fact, some alloys are too tough to even raise a bead
in, for bead setting stones. Except for exceptional cases, I always
use a rolling-type alloy for all my work, so I can roll out any
stock I need, and cast with it as well. You will want to remember
that even a bit of a casting (brittle) type of alloy, mixed in with
your new metal will cause problems, in my experience. If you don’t
know what type of alloy you are dealing with, then getting it to roll
out will always be a crap- shoot. Scrap metal is not fun to work
with, as it has very inconsistant results, all through the process.
If I were you, I’d take the whole lump and send it into a refiner, to
get your pure gold back out of it. Do your homework and buy a good
rolling alloy from a refiner, which rolls well and has a color you
like, and use that for your alloying. You’ll be amazed at the
results. Good luck. I hope that helps.
Been there, and gave up. I’ve got the Delft casting system so I made
a master out of aluminium and used the gold to cast the ring. It
worked very well. See http://tinyurl.com/24rgm4 for piccies. The
aluminium master was just rolled and bent without being joined. The
seam was filled with epoxy.
There are a lot of experts on this, but here’s how I do it. After
casting your ingot, rinse and wipe it dry. Any 'ol paper towel will
do. Anneal to a red color and keep the metal red for 1 minute for
each milimeter of thickness. (This is important- dont rush it) Let
it cool for about a minute. Put it in the pickle. It should not make
a whole lot of hiss when you quench it. If it does, you’ll have to
re-anneal. Go ahead and roll it two or three times, making sure that
you feed the ingot in the same direction each time. Don’t flip it
around. Then reanneal the same way. Keep an eye on the metal to look
for cracks developing. If they do you may have to fuse them back
into the metal while annealing. By the way, stop rolling at the first
sight of cracks and go straight to the annealing process. When you
get to the thickness you want, anneal one last time. Bending the
metal will harden it so don’t worry about the gold band being soft.
Having said all of this, if the mystery gold was dental gold, I’m
not sure you will have any success with this. They alloy dental gold
so it wont “dent” or distort while you’re chomping on that tooth for
20 years so that gold is meant to be really hard so it won’t bend.
(hopefully that was not the mystery gold) When you are peening on
the cracks, you are work hardening that spot in your metal. You will
have to anneal after you do this. (But why? Just fuse the cracks.)
Also, don’t pass through the mill twice at the same thickness. You
are work hardening the metal and it will probably crack. One last
thing, when you are annealing, try to keep the red color even accross
the ingot so that the metal is the same “softness” across the whole
ingot, otherwise you will get unpredictable results when passing it
through the mill. Good luck.
I’d suggest a complete cooling between heating to a bright cherry red
and rolling, then pickle, I wouldn’t hit it with a ballpean hammer
before rolling as that is going to compress molecules and thus
increase the incidence of cracking. In the case of cracky gold I have
sometimes allowed it co cool until the metal no longer gows and
quenched in alcohol. this has served me with gold that had a small of
white gold contaminatingthe mix. hope it works for you too…
I have just repaired a 9K ring that had a similar origin, although
instead of being forged/cold work this one had been cast out of
stamped 9K scrap jewellery, being made out off of essentially mystery
metal I was left with no option but to cut out the shank (the feature
portion although slightly cracked was salvageable) and replace it
with a piece of “D” wire rolled to shape.
I think you will find that the ring will continue to crack right
through its life till it finally fails, this may happen quickly or it
may take a long time, who can know? I would have sent the metal for
refining and used the value to buy metal of a known quality, just my
opinion, good luck with the project.
it sounds like you’re working with a 14k alloy for casting not
rolling.
I’ve experienced the same thing melting down my old castings or
buttons and trying all the same remidies that you list here- and
having the same results! It is very frustrating indeed!
We don’t use customers’ gold for rolling- it just doesn’t work.
(Unless it’s really old stuff that was created with the classic 3
part silver, cooper, gold alloy- then you can take all kinds of
liberties with it)
If you’re going to roll sheet or draw wire use an alloy meant for
that- we’ve used PM West alloys and found them to work really well-
the casting alloy works great for casting and the rolling alloy lets
you draw wire and roll sheet with very little time out for
re-annealing. PM West is also very good about advising us self-
taught types on technical issures.
Aimee- You may try to let it cool completely before you try to roll.
My best advice is to scrap the metal out and start with fresh. The
"mystery" gold is probably what contaminated your 14k. I’ve done tons
of 14k rolling in the past and never had a problem as long as I knew
that there was no solder or contaminates in it. When ever I have a
customer who wants to use “their gold”, I always advise them that I
cannot guarantee the results unless it’s refined first.
Lots of suggestions rolling in. I had a similar situation last year
where a colleague asked me to make a name bracelet for him using a
lot of scrap gold(14K) that he had collected from various relatives -
old earrings and the like. I am still a novice, so very quickly ran
into the very problems you are facing. I tried and tried but every
time I got the gold rolled out not almost where I wanted it, cracks
would form, and once, I actually got the thickness needed but when I
tried to bend it… bing… it snapped in half. So, I consulted my
mentor who suggested the following steps to “clean” the gold. First,
melt it down and throw in a pinch of potassium nitrate followed by a
pinch of sulphur (yellow sulphur - do this in a well ventilated
place!), when the “slag” forms, lift it out with a graphite rod.
Pour the ingot as usual. Try rolling out again but use the alcohol
quenching method that has already been described to you. I tried
this and it got easier but did not fix the problem. I went through
the process three times and ended up with an ingot which was very
well behaved and allowed me to complete the project. I’m no chemist
and have no clue how this process works, only that it did for me.
Whatever you try - good luck as I know how frustrating those little
cracks can be…
I really do appreciate all of the feedback you have given me on
this. To answer several of you on this, the mystery gold was part of
an old pair of cufflinks. It took longer to melt than the other
pieces and after we poured the gold, the crucible was pitch black! (I
am still not sure what caused this to happen-- thus I am calling it
mystery gold.)
Anyway, I will try with it a little longer, heeding as much of all of
your advice as possible. Hopefully this time it will work (I know it
is a slim chance and I will consider myself lucky), but I have
learned my lesson on accepting jobs like this one in the future-- no
thanks!
an old pair of cufflinks. It took longer to melt than the other
pieces and after we poured the gold, the crucible was pitch black!
(I am still not sure what caused this to happen-- thus I am
calling it mystery gold.)
Likely what I thought from the first post - the cufflinks were gold
filled, which is to say brass. The quote pretty well says just that -
all the symptoms. It may be that you can salvage it with some of the
methods people have posted, or just re-refine it. Certainly if it is
so, then your 14kt is no longer 14k (or 18 or whatever). Certainly
there are many solid gold cufflinks - I just worked on a pair - but
there are far, far more gold filled ones, or at least the findings
part.
I am sending the whole piece to DH fell Co. in LA to have it
refined. The client wants to be with me when we heat it up again and
re-roll it. Hopefully DH Fell will come through for us!
Just to add-- letting the ingot completely air cool after annealing
DID really help keep it soft.
Just to add-- letting the ingot completely air cool after
annealing DID really help keep it soft.
Then lord knows what you have in that alloy. All yellow golds are
mainly gold, copper and silver. Any yellow gold alloy will get
somewhat to a lot harder if allowed to air cool so what ever the
contaminant is in there is somehow negating this effect. Quenching
can sometimes cause thermal stresses that may cause micro cracking
that later shows up in rolling but it in clean metal will still be
softer than air cooled material.
James Binnion @James_Binnion
James Binnion Metal Arts
Thanks for all your advice on rolling out the gold. I had the
contaminated stuff refined. Today we melted, poured, rolled, bent,
soldered, formed, filed, sanded and polished a gorgeous 14K gold
ring. Thanks again for your help!