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Sorry if this doesn't belong here, has anyone had experience working gold.

I've got a couple of chains, a pendant and an old ring that I have been thinking about melting up to make our lass a ring. I have considered either having a go at lost wax casting or forging (my first choice). What I wondered was should I forge it hot or cold? does gold suffer from work hardening and if so whats the best way to anneal it? am I barking up the wrong tree altogether?

I have found info on lost wax casting and actually smelting the gold but not on forging. Any advice will be appreciated.

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You might want to look at "The complete Metal Smith" by Tim McDreight published by Davis Publications

It is geared to metal work for jewlers and precious metal craftsmen
Given the current value of gold and the history of fraud in gold chains I would be reluctant to melt together a gold ring of relatively certain karat value and gold chains of uncertain value. Just a thought.

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Thanks to both of you, the book link is great. I am not too bothered about the gold content as nothing I make is going to be for resale and wont be hallmarked, but I think I might melt the chains separately just in case.

Cheers

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Check out the karat stamps on the jewelry. If it's around 18K then the quality will be just fine, but even 14K will be okay. You can even mix together jewelry of differing karats (14 and 18), you won't be able to claim a specific karat rating for the finished ring (which you said was fine since you won't be reselling it or hallmarking it) but it will still be a gold ring.

Obviously remove any stones from the jewelry first. Also cut off any bales, jump rings, clasps or obvious solder areas (usually appearing as darker seem lines or areas. File these areas well to get any remaining solder out - this stuff could give you major headaches when you melt the gold down and. Jump rings are usually made of non precious metals plated in gold and bales and clasps often have steel parts inside them which you DEFINITELY DO NOT WANT IN YOUR GOLD.

Once all you gold is "cleaned up" puddle it (melt it into a blob) with an acetylene torch in a crucible -do not use any kind of steel or iron containers/ladels. If you don't have access to a refractory crucible, a charcoal block with a small dished out section will work, so should a clean refractory brick with a dished out section. Keep heating until the gold puddles into one lump.

As for your casting, lost wax is fun but modern lost wax casting takes a lot of specialized equipment.
You could also look at doing some cuttlebone casting (google cuttlebone casting) which is as ancient as it comes and really easy to do. It also gives the casting a really interesting tecture.

Good luck and have fun

Sam
-I've been taking silversmithing and jewelry courses since the fall and it's a lot of fun.

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Back again.
If you want to try some primitive lost wax casting you could check out a site called "Viking Bronze Casting" which talks about how you could cast bronze without all the modern tools we use today. I actually tried this in a one-day class a few years back. While the results were not quite what I wanted (due to errors on my part), the theory behind it is sound - and the same technique could be applied to gold and silver.
Basicly the whole idea is that you make your furnace, crucible and casting flask using cob (a clay, sand and straw mixture) and you heat it with charcoal and a bellows - really primitive.
You make your wax model, spru it and attach some wax wires for vents and then coat it in a thick layer of fine clay slip. When it's dry, you encase everything with clay-cob and fashion it into a casting flask. You then cure the flask in the charcoal furnace upside down so the wax burns out.
Keep the flask hot in a smaller charcoal fire while you melt your gold in the main furnace.
When it's liquid, turn your flask right-side up and pour your gold into the spru opening (basically doing a gravity cast rather than a centrifugal cast which is the modern method). After a few minutes, plunge your flask into a bucket of water. Don't remove it from the water orelse you'll spray scalding water everywhere. When the flask has cooled sufficiently, break apart the flask and get your cast. Be careful it may still be hot for a while.
Trim the vents and spru, file and sand to finished shape, buff and polish.
Cheers.
Sam

Edited by Aeneas
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So far all this has been about gold casting which is how rings are usually made. Now, you could cast a basic ring shape using any of these methods and then cold work the ring into final shape and texture - I think a "hammered" ring (with hammer mark txturing) would look really good, especially for the wife or daughter of a blacksmith.

If you're thinking about hammering the gold into sheet or a billet and then hammering it into a ring, you are going to need to get gold solder from a jewelry materials supplier. The solder is rated by karat (so the colour matches) so you're going to want as close an approximation of what the average karat is in your gold mixture.

Please post pictures of your ring when it's done - I'd love to see it.

Sam

Edited by Aeneas
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Google "steam casting" if you want and fairly inexpensive way of lost wax casting. It uses a method of using steam to force the metal into the burned out mould and a small propane camp stove and clay flower pot to burn the wax out. I have tried it and it does work.:cool:

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Blimey Aeneas's I wasn't expecting that much info thanks a lot. You dont mention using flux, I watched some clips on you tube and a lass was doing some centrifugal lost wax casting and she was using boric acid as a flux (although I think she was casting silver).

Initially I had been considering trying to hammer a billet out, but I do like the idea of casting, i'll have a look at cuttlebone and steam casting on google first and see if I can come up with something for a one off.

Do you know if a mould made from plaster of paris is feasible?

I ordered "The complete Metal Smith" by Tim McCreight off Amazon yesterday so i'll see whats in there as well.

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Glad to help.

I did foget to mention fluxing. A bit of borax during puddling and also when you cast is a good idea.

Plaster will not make a good mould. The investment casting houses use looks like plaster but it isn't. Investment has to be fired like clay in a kiln and the cast has to be made while it is still hot.

A plaster mould would still have too much moisture in it and the whole thing would explode when you poured the gold in ... That would be bad.

The Complete Metalsmith is a fantastic book for anything jewelry related - I need to get one for me too.

I hope you have fun with your ring.

Sam

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Glad to help.

I did foget to mention fluxing. A bit of borax during puddling and also when you cast is a good idea.

Plaster will not make a good mould. The investment casting houses use looks like plaster but it isn't. Investment has to be fired like clay in a kiln and the cast has to be made while it is still hot.

A plaster mould would still have too much moisture in it and the whole thing would explode when you poured the gold in ... That would be bad.

The Complete Metalsmith is a fantastic book for anything jewelry related - I need to get one for me too.

I hope you have fun with your ring.

Sam


My mate is a school technician and he'd suggested plaster of paris the other day for an aluminium casting project i'd been considering for my chopper. We can use the school equipment which includes a pottery kiln so happen we would have fired the mold in the kiln first. He thought the plaster would have had a better finish than sand.
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Actually you can use plaster of paris as casting materila but not straight.
I don't remember the formula at the momemt unfortunately. I would spring for jewlery investment since you are probably playing with some significant $ in gold.


Thankyou Charlotte, i've ust had a quick look on google and found that it needs sand adding about a 50 / 50 mix and silica and it still needs heating up to drive off the water. I need to read up a bit more.

"I would spring for jewlery investment" We Yorkshiremen have a motto

See all, 'ear all, and say nowt
Eat all, drink all, and pay nowt
An' if tha does out for nowt
Do it for thissen

Were born with deep pockets and short arms:):):)
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I have made some open ended iron rings that were sort of a rams horn design. It works in iron but gold is too soft. You might try twining the drawn-out ends though... that could work with or without solder. Of course for this type of product you will want hard solder... preferably of a true karat match (which is available).

Another approach would be to create a coin-like disk and punch a hole then drift and forge so that you have an unsoldered ring... this might be nice in iron too. Similarly you might slit a rectangle, drift and forge.

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  • 1 year later...

Sorry if this doesn't belong here, has anyone had experience working gold.


I've got a couple of chains, a pendant and an old ring that I have been thinking about melting up to make our lass a ring. I have considered either having a go at lost wax casting or forging (my first choice). What I wondered was should I forge it hot or cold? does gold suffer from work hardening and if so whats the best way to anneal it? am I barking up the wrong tree altogether?


I have found info on lost wax casting and actually smelting the gold but not on forging. Any advice will be appreciated.


I am not sure about the alloys of gold, but pure gold like you can get in ingots or bars can be forged just like steel,copper, or pure silver. If you want to forge these metals and change the dimension drastically, it is best to do it at a forging temperatures, but like all forgeable metals you don't want to over heat them. Copper, silver, and gold are very similar and can be safely taken up to a red heat and they will respond like yellow hot steel for quite a while compared with steel. After bright red it can melt quicker than you may think. Try copper before silver or gold and you'll see what you are up against. Also, you'll need to have a sound bar to start with, no air pockets, impurities, or burrs.
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The alloys of gold forge OK according to my personal jeweler. He said they all work a little different than 24K but like all metals they do need to be annealed from time to time becaues of the baser metals used(like copper). If you have worked fine silver vs. sterlig silver you will get an idea of the difference he told me once upon a time when I was at his shop considering make up some stuff for my wife. The cost of the danged stuff changed my mind in a hurry though. :blink:
Here is a link to some of the more common alloys of gold http://chemistry.about.com/od/jewelrychemistry/a/goldalloys.htm and here is a calculator to help determine the percentages needed to make the proper alloy http://www.artjewelrymag.com/Resources/Calculators/2009/03/Alloy%20Calculators%20Determine%20ratios%20of%20metals%20to%20make%20your%20own%20alloys.aspx

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