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Casting with stones


#1

What to do to prevent burning diamonds or making on them a milky
fire scale in process of casting with stones? Burning
temperature was 1050 F for 7 hours. The mold was grey, so
burnout wasn’t complete. It didn’t affect rubbies, but did
diamonds!? I’ll appreciate a prompt reply. Stan

e-mail: Stan@succeed.net
Phone: (916)749-0240; please feel free to call collect


#2

hi stan, add about 3% boric acid to your investment. the boric
acid will protect the diamonds, but may harm the corundum. i
don’t know why the corundum would not burn and the diamonds
would. precious metals west has a lot of info abut casting
stones in place. sorry, i don’t have the number handy.

geo fox


#3
       precious metals west has a lot of info abut casting
stones in place. sorry, i don't have the number handy.

Stan:

Here’s the contact info for Precious Metals West.

Precious Metals West / Fine Gold
608 S. Hill St. #407
Los Angeles, Ca. 90014
1-800-999-7528 / 213-689-4872
Fax (213)689-1654
http://www.paleoart.com/pmwest/pmwweb1.htm

And here’s the info from their “stone in” casting page:

Stone In Casting concepts…

  1. Things you need to know

This is a more exacting casting process that differs
only slightly from traditional casting/finishing.

A. You must plan to sprue for a low flask temperature at
casting. See chart below. Use a dark strong wax.

B. You must exactly match stone size to the wax model
being set. Sieve your stones.

C. You need 70% new metal in each cast. This metal
needs as low a flow temp as practical.

D. You slow cool the flask at least 1 hour to "hand cool"
temp., then blast off investment with a pressure washer.
Do this in a enclosed cabinet to recover stones that come loose.

E. You must tumble finish instead of stripping/pickling.

F. After casting wash, check for missing stones. Then clip
items off of tree, grind ~ tumble finish.

G. This is a proven technique in lOkt & 14kt yellow gold set
with diamonds, rubies, sapphires,cubic zirconia. All others
subject to experimentation/frustration.

  1. Co-ordinate modelmaking with stone setters. Train your wax
    people with setters. Apply quality inspections to the waxes
    before investing. All wax flaws will faithfully show up in the
    casting, everytime.

  2. Be sure to run a large button to assure orderly freezing of
    the metal, that is to prevent shrinkage porosity. Sprue with
    this in mind.

  3. Flask burnout chart… (All flask temps in Fahrenheit!)

Steam dewax first!
250 to 350 ramp 1 hour
350-450 ramp 1 hour
450-650 ramp 1 hour
650-850 ramp 1 hour
Cast at 850

  1. Gold notes- Use a Karated gold that flows no higher than 950
    centigrade. Our #21ce or #34 is a good start for lOkt-14kt. Use
    the most accurate, fast melt you can. Temp control is
    essential to this technique. Be sure to run a large button
    to assure orderly freezing of the metal, that is to prevent
    shrinkage porosity.

  2. Slow cool flask until you can pick it up by hand, blast
    off investment in a enclosed cabinet (if you need to recover stones)

  3. Decide how to spend all the setting money you saved.

Do be sure to test these concepts with care. This info was
gathered by Daniel, from the seminar given at MJSA EXPO N.Y.1996,
and from the kind assistance of numerous customers of PMWest.

Tom LaRussa


#4

Hi, Here’s a question :slight_smile: I read in “The Complete Metalsmith” (a
great book) by Tim McCreight that you can cast some stones as
part of the wax model. His list included rubies, diamonds, etc.
He also included “synthetic transparent stones” which I took to
mean zirconia. The descriptions match. Has anyone done this
before? One of my students wants to give it a try with a ring
she’s making, and according to the book it’s possible, but I
wanted to hear some real-life thoughts on it. She’s casting a
sterling ring, small and wants to include a colored piece of
cubic zirconia, (very small, like 1mm in diameter). We both thank
you for any replies, ( We because I’ll try it first with one of
my pieces that would look great with a small ruby :slight_smile: ) Terry
Swift


#5

Hi,

I have done casting with stones quite successfully. I used
white, yellow, pink, and purple cubic zirconia as well as blue
and green synthetic spinel. I was casting sterling silver using
a standard burnout cycle with a final flask temperature of
1000F-1100F depending on the models and a metal temperature of
1850F. I was using United Precius Metal’s deoxidized sterling
’D’. I have read the when casting genuine stones, the burnout
cycle should be a gradual rise to 800F and a hold there of at
least ten hours to burnout and then cast at 800F.

If you have any specific questions, feel free to e-mail me
directly.

Chris Maugham
Jewelers of America Certified Master Bench Jeweler


#6
   Tim McCreight that you can cast some stones as  part of the
wax model. His list included rubies, diamonds, etc.  He also
included "synthetic transparent stones" which I took to    
mean zirconia.

One of my classmates casted several small synthetic rubies in a
wax mold of hers and here were her results.

She found in two instances the stone “floated” or moved enough
that the metal partially covered the stone.

One was completely buried in the ring and one came out well.
None of the stones cracked.

Out of four castings, only one was sucessful.

My only advice is to try it out and play around with the
process. Another student performed an inclusion casting of a
copper rod placed in wax and then cast in silver. The ring is
smashing, but technically, the casting was unsucessful because
the silver was supposed to completely capture the rod. The
silver only partially covered the copper, but the result was
great and its success came from a happy accident.

My plugged nickel’s worth.

Karen Christians

Fly Fish Design
282 Lexington Street
Woburn, MA 01801
781/937-3827

@metalart


#7

Terry, I have done this many times and it works fine but there
is a very serious risk from time to time of stone breakage and
burning. I usually use a four inch perferated flask and mix in
the cold investment about a tablespoon of boric acid very well(
some warm the water and mix the boric acid then put it into the
investment but working time is much shorter). Then I paint boric
acid and alchohol on the ring wax with stones in it and then
vacume. I burn out till the temp gets to about 1200(never more)
and let it sit there at that temp. for 2 hours. Pour the gold
and LET IT COOL to room temp. and dig out. do not plunge! more
important then that is mking sure you have the least amount of
wax holding the stone and you have area under stone very open as
well as much as you can on top or you could have the stones
diappear into the ring and you’ll wounder what happened.

I don’t use this process as much as I used to as I get better at
setting but in certian situations i will. one more thing is
that if you have two stones or more next to each other make sure
they do not touch and are alittle bit movable to account for
shrinkage. Experiment first and be very watchful of each step.
The other thing I don’t like about the process is that you have
no way of polishing the seats and you have to carve your seats
with great care so you don’t have to trim metal away from stone
afterwards.

Remember this is not for the faint hearted or on stones that you
cannot afford to replace. I will only do this on diamonds myself
but have heard about doing it with CZ but I wounder why. Any
Questions just ask…Ron


#8
  He also included "synthetic transparent stones" which I took
to mean zirconia.  

I’m not sure about cubic zirconia . . .I’ve always heard that
they do not withstand heat very well. Yet, I have seen CZ’s
incorporated into lamped beads. I’ve often wondered how they did
that.


#9

Remember this is not for the faint hearted or on stones that you
cannot afford to replace. I will only do this on diamonds myself
but have heard about doing it with CZ but I wounder why. Any
Questions just ask…Ron

Ron,

I’m confused. You WILL do this with diamonds?

Seems like CZ and syn. corundum would be the “stones” of choice
for this method. They’re hard, so they aren’t likely to be
crushed by the shrinking metal, and they are cheap, so it
doesn’t matter so much if you mess up a bit. Am I missing
something?

Tom


#10

Oxidation plays a role in bimetal casting. While it would seem
that casting gold alloys around a niobium insert would work, it
doesn’t. One of my mentors regularly cast gold bezels in his
waxes- and ran a wax bead up the seam in the bezel wire. Worked
great, and it was a real time saving trick.

For some reason, I have trouble understanding why it is
important to cast stones into a casting. Remove the stone, cast
the piece, set the stone. It will probably look better, and you
won’t go through the agony of wondering if the stone will survive
the casting process. The setting time is shorter that the time
it takes to dig a casting out of cooled investment. The stones
that will survive the abuse of casting will probably survive
setting.

Rick Hamilton
Richard D. Hamilton
Martha’s Vineyard
USA
Fabricated 14k, 18k, and platinum Jewelry
wax carving, modelmaking, jewelry photography

http://www.rick-hamilton.com


#11
   For some reason, I have trouble understanding why it is
important to cast stones into a casting. Remove the stone,
cast the piece, set the stone. It will probably look better,
and you won't go through the agony of wondering if the stone
will survive the casting process. 

hi rick,

the points you make about casting stones in place are accurate.
the attraction for me was just to do it, so i did once. the
reason large manufacturers cast stones in place is cost. in the
case of channel setting multiple rounds and baguettes, western
manufacturers can’t compete with cost of labor so they compete
technologicaly. a great wage in china is $40-70.00 per mo
according to a friend who does business there. that’s a lot of
set baguettes for $40-70.00.

however, i’ve repaired and tightened more of these stone cast
in place rings than i care to admit to. my opinion is, even
after careful modeling, ‘setting’, inspection and burn out,
these manufacturers still can achieve only a second to a stone
set after casting.

best regards,

geo fox


#12

I agree with you Rick, the only advantage to casting stones in
place that I can see is if you are manufaturing large quantities
of inexpensive. low margin jewelry, it will save time. I dont see
how you could get a perfect polish under the stones. I think its
fun but doesn’t give you a better product.

Mark P


#13

In that case you would probably be putting the stones in the
silicon rubber molds prior to wax injecting them. Clean up and
finishing by tumbling would probably diminish the production
rate. If it were really worthwhile, school ring companies like
Balfour would be doing it. They have all the latest technology
stuff- including CAD-CAM.

Richard D. Hamilton
Martha’s Vineyard
USA
Fabricated 14k, 18k, and platinum Jewelry
wax carving, modelmaking, jewelry photography

http://www.rick-hamilton.com


#14
   Clean up and finishing by tumbling would probably diminish
the production rate. If it were really worthwhile, school ring
companies like Balfour would be doing it. They have all the
latest technology stuff- including CAD-CAM. 

Next time you have a Stuller catalogue in hand, look at the
pictures. Trees with maybe a hundred models spruued for casting,
and look! Don’t those waxes contain stones? They aren/t Balfour,
but I’ll bet that they are turning out similar production.

Bruce D. Holmgrain
e-mail: @Bruce_Holmgrain
http://www.knight-hub.com/manmtndense/bhh3.htm
snail mail: 311 Sugarland Run Drive, Sterling, VA 20164
phone:: 703-593-4652


#15

Coming in at the end of the thread he decloaked and said…
Balfour might do it but I don’t think they have the need.(I used
to work for T&C) Anyone who can accept the lower quality setting
job can make use of it. It is WORTHWHILE if done properly.


#16

Would be interesting to know if they are doing that in production,
and really casting stones in place,or if it was done as a lark for
that photograph.

Richard D. Hamilton
Martha’s Vineyard
USA
Fabricated 14k, 18k, and platinum Jewelry
wax carving, modelmaking, jewelry photography

http://www.rick-hamilton.com


#17

Hi Richard, Casting stones in place has been largely pioneered and
perfected by the folks at Romanoff in NY. My opinion is that it is
used for an edge on the bottom line for production folks. There
probably would be a creative case for it with diamonds. I wouldn’t
take the risk for myself with a nice ruby, but I understand the
process. Call Romanoff for more info at 800-2217448.
Mozeltov…J.A.


#18

I’m not sure that they are using the processs but it is Real
Production Stuff,Rick


#19

John/List … Casting stones in place has been around in secret (
Don’t forget … The Big Secret is … there is/are no secret(s)
) since the early eighty’s. I did it with CZ’s in 1982 on brass
alloy sample castings but found the quality of the final product
was not representative enough of the final product and did not
pursue it. Others were working on it at that time.

The issues are well developed. Methods have been described that
vary from simple ( stuff a stone in a pre-cut setting) to very
complex ( mount the stone in a rubber mold and shoot the wax around
it ) and everything in between. All have been successful and I have
practiced many of them. Understand the physics of the casting
process(es) and you’ll find all the answers.

Romanoff holds no corner on the knowledge base for this process.
See the Proceedings of the 1997 Santa Fe Symposium.

Paul Finelt


#20

Paul Finelt

It would be a great process to develop for white metal casting- I
did help develop a process casting thermosetting resin around
metal inserts back in the early 70’s.

I do a balance of waxes and fabrication in my work, and few stones
besides diamonds would stand up to being cast in place anyway.
Tahitian pearls, tourmalines, color change sapphires? Well maybe
the sapphires. So casting in place has its merits for production,
especially with the synthetic stones that can stand the heat. I
understand the facination, however.

What have you done with casting colored alloys together?

Rick Hamilton
Richard D. Hamilton
Martha’s Vineyard
USA
Fabricated 14k, 18k, and platinum Jewelry
wax carving, modelmaking, jewelry photography

http://www.rick-hamilton.com