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Enameling on 18k green gold

Hi folks,
I am enameling a ring that is 18k green gold. This is a cast piece that will be soldered (with hard solder) to a ring shank. Once the ring is assembled I will be enameling. My casting is 750 gold and the alloy mix is 38% copper, 60% silver, and 2% zinc. I will be using transparent warm colors of enamel.
1- should I depletion gilding the Metal? What is the best chemical?
Sulphuric acid or nitric acid?
2- if so…use unleaded enamel?
3- any other helpful tips?

Hi Beth,
I’m a metallurgist and don’t have much knowledge about enameling, so I won’t be able to answer the questions in your post.
Unfortunately, the alloy you have chosen when melted with fine gold will result in a 18K gold that will have standard yellow color. Only zinc is at the proper amount to help with enameling. You should consider an alloy mix (what is also known as master alloy) that has about 5% copper, 93% silver and 2% zinc that would give you a fairly rich 18K green gold.

Thanks. Is the zinc necessary for a nice casting? I think it is not good when enameling. My casting looks yellow so your response is helpful.
I am curious (now that I have researched, I heat there is a green “enamel” gold that I should have asked for. I’m not sure of the composition.

Enamel gold, which is 18K and can be greenish, has no zinc in the alloy.

Is the zinc necessary for a nice casting?
Yes, presence of zinc prevents copper from oxidizing and results in somewhat smoother casting surfaces.
I think it is not good when enameling
Yes, zinc could vaporize at the temperatures used during vitreous enameling and create bubbles under the enamel. I believe, 2% zinc in the master alloy (or 0.5% in 18K) is a nice compromise to get sound casting and not have problems during enameling.

Thanks! This is helpful!

Does the green gold actually show up enough to matter? Seems like a lot of hassle for this project when you know 18kyg will present the least problem.

You are so right Barbara! My customer wanted green gold. I had also read that green gold plays well with enamel. I am not sure whether green or yellow make a huge difference. I have learned a lot about the process in the meantime. In order to enamel on gold it has to be depletion gilded first. Then a flux…on gold Bovano (Soyer )#2 flux is what is used. Enamel Art Supply has some although it’s not on their web page. If you send an email and request it, it is available. I won’t have time to finish the ring until next week but I’m hoping to post a photo with good results!

The difference between “green” gold and yellow gold is that it has more silver in the alloy, plus maybe some other metals, not an expert in that. If you want a red gold, that means more copper, which will make it harder and more brittle (the copper). Someone posted an alloy spreadsheet a while back listing the metals in various alloys–search for it in the archives. HTH!

I am disappointed my caster did not give me exactly what I asked for -18k green gold. My ring is more yellow and when I called to ask what alloys they used I found out it was more of a yellow mix. At that point my customer was more anxious about getting the ring than the color.

If you saw the error initially, I would have discussed HIS error. Agree on paying for his gold, but not his casting labour. I’d let him know that your customer is angry.;(
I’d look for a new caster. I’m sure that there are many more in our ‘very tightly knit group’.;(

Gerry, on my iPhone

I agree with you. My customer chose to proceed.