Question: alloying gold

[Brian Hochstrat]

Being I work quite a bit in colored golds, I have given thought for quite a while to alloying my own, so not to be limited by a suppliers palette of colors. So I have decided to make the jump. I have an idea of how it is done, but not 100% sure, being I have never actually done it or have even seen it done. So I figured you goldsmiths out there could get me on the right track.

So here is my plan, supplies and the questions in that plan.

Crucible and tongs
rolling mill and draw plate
oxy/acetylene torch
ingot mold

Ok from what I understand you weigh out your mix and put it in the crucible and heat(when melting the gold, do you use direct heat or indirect or both? also do you use any kind of flux to prevent oxides from forming or is that an issue? On the torch what type of flame is better, as in carbonizing/oxidizing/normal?)

Then you pour it into the mold, (do you have to prep or preheat the mold in any way to achieve a good flow? Is there any special method used to pour the gold to reduce porosity?)

Next pull gold out of mold and roll and draw into the desired shape.(I use a draw plate a lot, but have not yet received my rolling mill so I have never run one. They look pretty straight forward, but is there anything tricky I should know?)
So as you can see I have only a basic understanding about what I want to attempt, so any advice, tips, tricks or links to that info, would be most helpful and much appreciated. Brian

 

[Brian Marshall]

Hi Brian,



My first advice would be to use oxy/propane... I'm not fond of acetylene for many reasons.

Second, melt the highest temp metal first and then add the lower temp metal grains gradually.

You may need a quartz or graphite stirring rod - not so much for stirring - which can be a bad idea, but to dislodge stuck or wandering granules.

You may want to invest in protective lenses - depending on what you are melting.

Yes, you should preheat the mold, other wise you may be picking the granules up off the floor for several days after a minor explosion...

Coat the inside of the mold, soot works well.

The pour must be a smooth motion. Turbulence causes bad ingots.

If you do use flux, and accidentally get some into the poured ingot, you will need a to pickle it off before you run try and run it through your mill.



Brian Marshall
SJAS
Stockton, CA USA 95209
209-477-0550
instructor@jewelryartschool.com
http://jewelryartschool.com/


P.S. If you get down this way to visit family, stop by and I'll make up some stock wire or sheet while you are here...

 

[eastslope]

Thanks for that good info Brian Marshall. I have been thinking about melting down my scrap silver into ingots and making my own sheet and wire. Just need the tools and mill to make it happen. Seems like all the cool kids have a rolling mill, so I want one. Why not acetylene? Just wondering since I already have a large acetylene torch, and a smaller pexto acetylene/air torch? Thanks again, Seth

 

[Roger B]

When using the wire rolling mills, work your way down gradually otherwise the wire will develop a sharp ridge from where excess metal has been rolled flat between the square holes (it is hard to describe but when you do it wrong you will know straight away). If this ridge forms it will have to removed by filing off before moving to the next stage which is - rotate the wire 90 degrees and thread through the same hole. On some mills which have only a few holes the rollers will have to opened up before using the next size hole.

Have fun,
Roger

PS. Expect to experiment with different recipes and in doing so spend a bit of money. Some colours and alloys may be too brittle to inlay.

 

[jlseymour]

Brian, go to
www.ganoksin.com
and search for alloying...
You could spend a day or 2 with Brian and that would be the ticket...
Seeya in Hotlanta and Scott's...
Jerry

 

[Peter E]

I don't have much experience with a rolling mill, but what I didn't see mentioned was annealing. It may be different on pure gold, but on the 14k gold I was rolling, annealing was needed before every pass, or cracks develop.

 

[Mario Sarto]

Hello Brian,
i am a German goldsmith for more than 25 years now. Please read my suggestions about your intention. There are a lot of mistakes possible doing this.

Please don't go watching videos from laymen out there. A lot of them are frightful, because those people are unlearned, they are not skilled!

I can teach you in a step by step with pictures/video here on the forum, if you like. Just tell me, how much material (in gram) you want to alloy at one time usually.

Best to you, Mario.

 

[Mike Cirelli]

Brian here's a step by step. http://igraver.com/makingwire/

I would suggest to you use premixed alloys from your favorite company. I don't mean with the gold already added, but thats an option. Gold is to expensive to be just throwing metals into it, then only to find out you can't do anything with it but maybe cast it. Use good rolling alloys. If you need any help drop me an email.

 

[Brian Marshall]

Acetylene is the "dirtiest" of the gases that we use. Simply note what happens when you light off an acetylene/ox torch versus a propane/ox torch...

You can actually "inject" carbon into the melt by using an improperly adjusted acetylene/ox torch. Think carbide crystals...

Besides being cleaner, propane/ox when used with a Meco midget torch is about the most versatile torch of the 9 torch brands we have in the studios & classroom.

And yes, I am well aware of the silversmiths torches that run on acetylene/air. Different animal entirely. There are 3 brands of them in the classroom. Large bushy flames are better for silversmithing. Not so good for precision or high heat jobs like soldering fine chain, melting, or welding platinum. Acetylene is NOT recommended around platinum.



Brian Marshall
SJAS
Stockton, CA USA 95209
209-477-0550
instructor@jewelryartschool.com
http://jewelryartschool.com/

 

[Kevin P.]

Brian, I would recommend an electromelt by Kerr or similar, ( pg 551 Rio Grande catalog) not a torch unless you want a torch for other purposes. Mike mentioned alloys ( pg. 548-49, also Rio) to check that out.
Alloying is not all that common. Don't read about it and try; find someone who does it on a regular basis and get some one on one. Someone like Jason perhaps.
For what you do it's probably the best way to go; alloying your own gold that is.
Good luck
Kevin P.

 

[Mario Sarto]

Brian here's a step by step. http://igraver.com/makingwire/

That is a neat step by step. One thing i suggest to do not: never put a hot bar/piece in a pickling solution to cool it down.
The behavior of a hot piece is like a sponge when cool it down fast in fluid. It has microscopic small holes and flaws which are wide open when piece is hot. If you cool it down fast, the piece absorbs parts of the fluid. In this case pickling acid. You never get this out until you melt it again. This little parts of acid corrodes the rolling mill and the draw plates. Furthermore (jewelry)pieces who are build in that manner gives the user a prickle for years...

 

[Kevin P.]

Brian another useful thing:"The Jeweler's Bench Reference" 68pp. 7" x 4" spiral bound.
Mine is an old one but it's still in print.

An example: Alloying
green-yellow gold 1.000 fine gold 0.222 fine silver 0.111 copper
orange-red gold 1.000 fine gold 0.048 fine silver 0.285 copper
weights in grams

On one page, 27 formulas for alloying golds
There are lots of basic things in this little book.

The standard on this forum seems to be: use only 24k gold for inlay.
But I've also seen photos of Alain L.'s work and Phil C's work on firearms. Gorgeous colors of golds. 24k gold is all the same color. The only way to get those other colors are by alloying.
There's also the possibility that those two are genuine alchemists even turning lead into gold! More likely I'd say they have methods of alloying that creates those wonderful colors.

If Mario were in the US, it sounds like he'd be a likely tutor. But do it in person face to face. Once you alloy you can't take the result apart. You have to send it to the refiner.
Kevin

 

[KCSteve]

Ha! I thought I remembered seeing a couple of threads about alloys and what it takes to get different colors:
http://www.igraver.com/forum/showthread.php?t=1849
http://www.igraver.com/forum/showthread.php?t=103

 

[jlseymour]

Brian H, a few day's with Brian M, would be a short course...
Take advantage ...
I'm wishing I was closer to CA...
Will be when we retire, sweet home Alabama and California...

Jerry

 

[Mike Cirelli]

Mario the bar in the tutorial is fairly cool by the time you get it out of the ingot mold, it's just a little to hot for fingers though. The bar can be left to cool by air also.

 

[James Roettger]

(1) I like propane oxygen because it's cheap and works great.
(2) You'll need different crucibles for all the basic karats and basic colors. It's okay to share yellow, green and rose but white golds should have an exclusive crucible.
(3)heat ingot mold till water vapor no longer forms on it from the torch and then coat with soot be reducing the oxygen, about 300'F
(4)use slightly reducing flame and a large #6 welding head to melt. Add a pinch of borax just as the metals start to form one blob.
(5)For best results purchase your alloy colors from various sources such as Stuller or Hoover and Strong. Be sure to purchase rolling not casting formulas. You can mix colors yourself but they will never be as workable as commercial alloys.
(6)Carefully weigh your ingredients. I put the gold and the alloy all in at the start and keep the mix constantly covered and protected from the atmosphere with the flame. All the metals will have to reach the melting point of the pure gold so it works just as well to throw them all in at the start. Adding them in sequence just opens up the mix to oxygen from the atmosphere and risks dropping a piece of alloy onto the counter instead of the crucible. You will have to push the mix up extra hot to achieve a thorough melt but draw back and reduce the flame once the melt is complete to avoid boiling your mix.
Use the stirring rod only enough to confirm you have no lumps in the mix.
(7) care for you rolling mill by keeping it constantly covered with a thick coat of motor oil. Remove any staining on the rollers immediately with 600 sandpaper.
(8) Quenching your stock in the pickle will draw acid subsurface into the metal and result in etching and damage to your mill. Always quench in pure water then pickle to avoid drawing acid into your metal.
(9)on the first roll of your just poured ingot you must always double the length of the ingot to create a grain structure. Rolling less than double the length will result in cracking on subsequent rolls. You can use a ruler to measure your first roll. Subsequent rolls can be whatever you want so long as you don't overstress the metal before annealing.

 

[canadian]

Brian,

Your best bet is to use Oxygen and natural gas. It is the cleanest mixture out there. On my website, on the tools page: http://www.artisticjewelrydesign.com/tools.asp you can see what I use - Oxygen Concentrator. It makes pure oxygen from the ambient air. You just plug it in and off you go. It will give you up to 5 pounds of pressure. Enough to operate 2 jewelers torches.
It is inexpensive and, safe and eliminate a need for any tanks.

If you need I can supply you with one.

Making our own alloys is not that difficult. With a little practice anyone can do it.
If you have any questions I will be happy to answer them for you.
Best,

Boris

 

[canadian]

Brian,

Your best bet is to use Oxygen and natural gas. That is what I use. Please see the link to my website page; http://www.artisticjewelrydesign.com/tools.asp

Here you can read up on the use of an Oxygen Concentrator. It makes oxygen from the ambient air. It will make up to 5 pounds of oxygen, enough to operate 2 jewelers torches. It is both inexpensive and safe, and eliminates a need for any tanks. If you need one I can supply.
Best,
Boris

 

[Brian Marshall]

Boris,


You must have a higher normal pressure in your natural gas lines up there than we do down here?

We had to install a booster (GTEC) to get enough natural gas pressure to melt & cast with...



Brian

 

[Brian Hochstrat]

Hi guys. Thank you all for taking the time out of your busy days to respond. If you all type like me, I figure I owe everyone about $70 shop time each.

With all this info I have a solid game plan. I wish I had the time to take a trip and see it done in person, but being Blade show is coming up fast, it is kind of crunch time around here. So I am going to take this info and have a go at it. Worst that can happen is I send a molten blob back to the refiners, however, I am 97% sure that won't be necessary. Thanks again, and when I get all my supplies and actually have a go at it, probably next week or so, I will post up the results, good or bad. Best regards. Brian