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Casting with bezels in place


#1

Hi all,

For some time I’ve been casting sterling items with fine silver
bezels in place, i.e. melting them into the wax before spruing and
burnout. I’ve had good results and it’s been a useful technique for
me. So I decided to do the same but with gold bezels instead of fine
silver. I wanted to use 18k but only had 14k in the width I needed
so I used it instead. Three pieces were cast in sterling with 14k
bezels, with a zero percent success rate. I guess I should have known
that 14k isn’t pure enough to take a 10 hr burnout cycle, the bezels
broke down and the castings had giant holes in them around the
bezels. So my question is will it work if I use higher karat gold?
Does anyone else out there do this? Any ideas would be greatly
appreciated.

Thanks for your help,
Douglas


#2

Could it be that copper is among the alloy metals in the 14K gold
bezels? That would produce the eutectic effect - where the silver
and copper get hotter where they touch than either alone? Maybe
someone else knows what is commonly used as alloy in the various
karats of gold. I imagine rose gold has more copper.

Linda Gebert
http://homepage.mac.com/lgebertsilverjewelry


#3

No it won’t work, the silver will eat up the gold simply because the
melting point is lower that that of any kt gold you may want to use.
Fusing is a great way to learn about how quickly you must move the
torch to allow the silver in liquidus to"grab" the gold appliques,
etc…you may want to experiment with…Mostly what you’ll get if the
gold is anything but very thin bezel stampings, or foil is a hole
where the gold was, and the silver consumed it- Though it could be
removed with a bright dip in the case of a foil, or thin applique’,
it is not worth the time involved to get a result that is pretty well
standard and common…It will definitely not survive a long burn-out
cycle…Ashanti casting though allows for the gold to be covered with
a refractory material, clay, charcoal and dung mixture-

much like a coat of ochre- but it will still leave a lot of post
casting clean-up to be done around the seam that must be pretty near
perfect if you want to try the process…and even then the results
are not always 100% predictable, nor can you tree many pieces, or
rather make a small scale production run with a wax model and 2
pours-1 gold, then blocking that off with a mixture (minus the
charcoal in this case as is used following the Ashanti method), and
the other in silver- far too much time spent when its easier done
differently with predictability being the key- at least I like
predictability- if you don’t then it may be worth your time to
experiment with a direct casting method that isolates the two metals
by creating two different pouring gates and sprues anyway gold is
still a bit too high to experiment with without loosing a good bit of
what you would need for your pieces…

rer


#4

Typical 14k yellow alloys have a melting point of 1490-1544 your
Sterling is in excess of 1640F as it is flowing into the mold. The
bezels melted instantly. You will probably see similar behavior with
18k yellow as you will be very near its melting point.

Jim

James Binnion
@James_Binnion
James Binnion Metal Arts


360-756-6550


#5
Could it be that copper is among the alloy metals in the 14K gold
bezels? That would produce the eutectic effect - where the silver
and copper get hotter where they touch than either alone? Maybe
someone else knows what is commonly used as alloy in the various
karats of gold. I imagine rose gold has more copper.

A small correction- metals don’t “get hotter” where they touch, but
they may produce a eutectic alloy that has a lower melting point
than either of the pure metals involved. (Temperature of the metals
is a function of the local environment, such as torch flame
temperature, kiln temperature, the presence of a heat sink, and
reflected radiant energy, to name a few variables.) As to the
question about the gold bezel: a 14K bezel is extremely likely to
have a large percentage of copper as part of the mix of base metals
in the alloy. Don’t forget the lower melting point of the solder
used to attach the bezel. So one needs to be aware of the mMP of the
sterling base, any gold trim, and the solder to be used. The
differences could be quie small.

Yes, rose gold has mostly copper as the alloying metal. The shade of
rose or pink gold alloys is influenced by other alloying elements,
such as silver and zinc.

Dick D.


#6
That would produce the eutectic effect - where the silver and
copper get hotter where they touch than either alone? 

Linda, a eutectic “effect” does not mean anything gets hotter at a
contact point. It refers to the way two dissimilar metals, like
silver and copper, or gold and copper, or silver and gold, when
heated to a temperature where there exists a potential alloy of the
two that melts at or below that temperature, will combine to form
that molten alloy at their contact point, even if the temperature is
not high enough to melt either of the metals individually. Thus in
the case of a contact point between copper and silver, when heated to
or above the eutectic temperature of the two, at the contact point,
an alloy of the two forms, potentially fusing the two together. But
this melting of the two to form that alloy at the contact point is
not accompanied by any rise in the temperature of that contact point
as a result. The melting point of the combination is lower than the
individual melting points, and that is why they melt. Eutectic
refers both to the alloy composition of the two metals that has the
lowest melting point, as well as that temperature at which that
combination melts.

Peter Rowe


#7

Hi everyone,

Thanks for all your help, I always wondered what ‘eutectic’ meant.
Well I feel kind of silly for not checking the melting point of 14k
before subjecting it to fully melted sterling in the flask. I like
the effect I get from this technique when it works, and I’d rather
not give up on the gold bezel/silver casting idea, so I’m wondering
if I can make it work w/ 22k.

22K has a melting point of 1790 so it should be possible in theory
as long as I keep the silver melt at a reasonable temp, right? or,
will it make a eutectic alloy and turn it to porous mush where the
two metals meet? I’m pretty uneducated when it comes to metallurgy,
I can bang on it but don’t really know the chemistry of it very
well, so thanks for all the help.

Douglas, in cold wet Sitka, Alaska.


#8

I have a friend who casts fine gold and 18K rose gold in silver, as
well as silver in 18K gold. I have no idea how she does it, or why
she doesn’t get a eutectic thing happening, but it is apparently
possible. I know it’s cast in place rather than soldered, because
she never solders. Here’s her site:

http://www.orionworks.com

Janet Kofoed
http://users.rcn.com/kkofoed