True Rose gold is neither hard nor brittle. 14K is harder than 18K, but both are easily malleable, and machinable. You may be referring strictly to 8-10K Rose gold which is somewhat brittle. Also, there was a Rose colored jeweler's bronze that is definitely brittle and hard.
I don’t know what experience you have working with these materials..
You may have had a B_ _ _ _ h of a time but the end results is simply superb, WOW!
I am primarily a silversmith. I have worked all gold alloys and poured and rolled hundreds of ingot from a couple ounces to over a couple pounds. I have made and used Purple gold. I even made a production run of Purple Sterling (it lost color after about ten years). I have hand formed, press formed, machined, and engraved most of the alloys I have worked with. I have never poured an ingot of 25% pure copper and 75% pure gold, copper has a great affinity of oxygen; I doubt most producers would, though I do think David Fell might. I have used Acetylene, hydrogen, natural gas, propane, and electro-melt for making ingots. I have extensive experience machining 14K and 18K gold with lathe and mills, and even more so of sterling (my personal metal of choice). I also have a great deal of experience machining, welding and engraving of steel (for tooling, not guns), several tool steels, copper, beryllium copper, magnesium, aluminum, and titanium (not welding). I have poured and worked several ingots of 18K made with pure copper and pure gold (I only use Canadian Mapleleafs, Kuggerands produce brittle results), and that alloy performs pretty much like sterling. I had a Saudi customer in the nineties that loved it. 14K alloys usually have a small amount of zinc, and then proprietary mix of other alloys (mostly de-ox because of coppers affinity for oxygen, the source of brittleness). Most commercial sterling alloys either contain de-ox alloys and/or are poured under very careful conditions (my preference). I have known producers who put out inferior sterling sheet for years and their customers don't seem to notice.
Shouldn't 'pure' gold, be 24k, .999, or whatever, regardless of its source? otherwise it's something other than 'pure'?
Kugerrands guarantee 1ounce of pure gold, not that it is pure gold. It has a small amount of impurity that causes its deeper reddish color. Canadian Maple Leafs are made from gold that is triple refined to the highest purity of gold you can get anywhere. I believe (from memory) that it is legally marked at .9999 pure, but could be marked at .99999, though that marking is never legally used, even in lab chemicals. At least as of the nineties.
Yes, all gold, silver, copper, palladium and platinum alloys work harden. Some faster than others. If at all possible verify that you are buying an alloy for wire and sheet rather than an alloy that was intended for casting. There is a big, big difference. Using casting alloy for sheet is the most common cause of all the problem engravers have. The second biggest problem, more so for silversmiths, is the continuous casting process. It sucks, but is cheap. Anytime you encounter an alloy (silver or gold) that is work hardening too quickly, switch suppliers, they are not using a wire and sheet compatible alloy, and probably continuous casting. For gold sheet and wire, I exclusively make my own, so I can't help you with a supplier. For sterling I used Handy and Harmon for years until that dried up. I tested around and settled on Stern Leach. I haven't purchased in awhile because I usually buy over a thousand ounces each time, and I have been on other projects the past 5 years. If you want to make your own gold alloy, use Canadian Maple Leafs and get your alloy mix from PM West Refiners if you can. United is good too. You can make your own gold sheet without a rolling mill. You will need an anvil and a decent forging hammer; and patience. After you've done it a couple times, it gets easier. The result is a mixed crystalline sheet with superior qualities to anything you can buy. The downside is the extra work. Don't forget to preheat your ingot mould. If you need a recommendation on forging hammers or anvils I can give those as well.
If your rolling mill is big enough, cross roll, at least during break down (the first 50% reduction, or about 40% for red gold). Also, with higher copper, it is very important to anneal in a dark area, and don’t exceed straw color heat. It helps to anneal on a charcoal block and still using flux. Good charcoal block is expensive. I run wood stoves over the winter and save chunks of hardwood charcoal and use that for annealing.
Thank you Silvermon, More good advice.
Krugerands, i think you mean, are 22kt .... that may be the issue you have had with your alloy.
