Melting Dental Gold

To make a long story short, a customer wants a very special knife, which is mostly built. But he wants embellishments on the knife that
I've never attempted before, so I'm seeking advice from the good and knowledgeable people in this group.
He wants a solid gold thumb stud, and he sent me the gold. It is, for the unsqueamish, a dental bridge and a couple of gold crowns, apparently harvested from his own mouth a few years ago when he plowed into a bridge abutment and ate the steering wheel. The doctors had to reconstruct his face, but they saved his gold teeth, which he sent to me for this project.
Yeah. He sent me his teeth. You can stop gaping now. Metal content ensues:
I've looked online and found that dental gold can contain lots of other metals, including platinum, palladium, silver and even chromium, copper and zinc. No way to tell what's in this guy's teeth. The fittings don't look like gold. They look like untarnished copper. They don't have the look of a 24 karat grille, but they are 40 years old.
I've melted and cast small gold parts before, but only from gold that was 100% identifiable in terms of alloy. This is a different situation. I have no way to know what's in this amalgam. I'm afraid to put a torch to it.
My tooling includes a heat-treating oven that can reach 2200° F, a propane torch and an AO rig. I have crucibles for precious metal melting.
How can I make this guy's thumb stud?
-Frank
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The only way to be 100% sure of the chemical composition would be to have it professionally assayed. Separately, you have to remove the extraneous or undesired elements. To be totally honest, I'd be tempted to tell the buyer to buy the proper alloy in new material. I think it is too hard to make a high-quality product from the jewelery equivalent of "mystery metal".
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"woodworker88" The only way to be 100% sure of the chemical composition would be to

^^^^^^^^^^^^^^^^^^^^^ "Splain to him that it is not a jewelry quality alloy, and offer him a choice--either buy some other gold, or play with this at his risk. What can you both lose? You could melt this down and make a simple casting, just to see how it turns out. It's not going to disappear, and will probably be more attractive (less disgusting) even if it doesn't work out for the knife.
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I think that if those teeth survived 40 years in the customers' mouth, they will survive on the decorative knife. The cheapest would be to pay a jeweler to cast them to the desired shape, IMHO.
I agree that it is a mystery metal, but its properties have already been validated.
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I'd say take the dental gold to a refiner (minus the bridge fittings) and trade it in for casting shot of known alloy and karat. The refiner will give you the value of the gold content, less a fee. That way, you won't waste your time messing around with an odd alloy that may not work with your casting process. Make sure to get enough to provide a button and sprue.
Andrew Werby www.computersculpture.com

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Look in your local yellow pages for "dental labs". Knock on a door or two; smile! Ask to talk to the guy who does the casting. Hopefully, he/she will give you a bit of a tour and discuss casting temperatures and methods. You might want to arrive late in the day, since the casting person is usually the last to leave in the evening. Don't be surprised to discover that person does jewelry casting "on the side" or as a hobby.
A dental lab is nothing more that a miniature foundry/machine shop. The dentist gives them a mold of the patient's mouth. From that, a technician designs the cap or bridge and carves it out of wax. Then the part is cast from dental alloy using the "lost wax" method. Not all dental alloy is gold-based.
Vaughn
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On Sun, 20 Apr 2008 10:37:56 -0700, Frank J Warner wrote:

Set the crowns into the handle for the thumb stud? It'll look as impressive as hell, in a very peculiar way.
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Tim Wescott
Control systems and communications consulting
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On Sun, 20 Apr 2008 20:19:35 GMT, "Harold and Susan Vordos"
(No snipage due to non propagation of original. See note to Harold at bottom)

Sorry to not add anything, but I know very little about this subject.
Harold, TDS is no longer propagating out to the rest of usenet. I reported this in tdsnet.general on the 12th and have received no reply. (Also switched my posting to Easynews / Forte APN.) Saw a post by you and remembered to look at it more closely *before* I downloaded the body. It never made it to either NSP I have configured.
Might want to check for your recent posts on Google groups. I think TDS was broke for over a week before I noticed.
--
William

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Replying to my own post, I melted one of the small crowns not attached to the main bridge piece with a propane torch this afternoon. It melted just like one of those old dimes I used to melt with my daddy's propane torch back in the 60s; the real silver lady liberty dimes.
The resulting lump was more silver than gold in color, so I suspect this amalgam is heavy with silver.
The bottom line is that it melted in a familiar way, so I'm probably able to melt and cast the remainder into a piece I can machine for a thumb stud.
The color will be slightly off. This knife uses pre-ban elephant ivory for the scales, and I'm using gold-plated screws to hold it all together. The thumb stud will be halfway between the color of the blade and the color of the screws.
-Frank
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wrote:

What about giving your dentist a call and see if he or she can tell you the composition basics and point you to a lab to get the finite details? Dentists may be worth something besides pain now!
All the best,
Rob
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The gold plated screws said it all.
What are they - 23 ctw ? color matching might be a nightmare.
I'd talk to the man and see if selling the gold (as is) to a dental lab and with that money buy the quality gold. If you need to cast and can't - there are jewelry makers that can.
Martin
Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net TSRA, Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal. NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member. http://lufkinced.com /
Frank J Warner wrote:

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I missed the Staff meeting, but the Memos showed that Frank J Warner
-0700 in rec.crafts.metalworking :

    Cool. At least it sounds cool looking.
    You may want to explain how it is that the "gold" bridgework melted down into a less 'gold' color.
tschus pyotr -- pyotr filipivich "I had just been through hell and must have looked like death warmed over walking into the saloon, because when I asked the bartender whether they served zombies he said, ‘Sure, what'll you have?'" from I Hear America Swinging by Peter DeVries
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On Sun, 20 Apr 2008 16:44:27 -0700, Frank J Warner wrote:

Show it to the customer. I if he doesn't want to come out and look tell him that it doesn't match and you won't be responsible for the aesthetics of the thumb stud - or get it in writing. Surprises to the customer can be painful all around, and they often change their minds over aesthetic issues like this. Seeing _is_ believing, but not all folks (even, or perhaps especially, those with money) are wise enough to know this.
--
Tim Wescott
Control systems and communications consulting
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wrote:

It's been cast once so you can probably cast it again. I seem to remember there's a way to remove nongold metals from the surface (an acid etch or something) You'd have to look for it. Karl
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snipped-for-privacy@gmail.com wrote:

Labs around here aren't re-using take-outs. Too many inclusions of things that create minor spattering and surprises.
Was there any Mercury alloying <grin> of dental Gold? /mark
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wrote:

For a variety of reasons that is exactly correct. In general, dental labs only use new alloy. They send all used metal to a smelting/recycling facility. Once a year or so, they even roll up their old carpets and send them out for smelting (like the golden fleece). Even the dust from their vacuums may get the royal treatment.
Vaughn
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On Apr 21, 12:03 pm, "Vaughn Simon"

I wouldn't use it either if I was a dental lab or a jeweler. Not worth the cost of failure. As long as his pattern is easily reproducible I'd give it a try. I do like the idea of mounting the unaltered dental bits though. Karl
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