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Enameling on gilding metal

Does anyone have experience enameling on gilding metal (95% copper, 5% zinc)?

I want to work with enamel on gold-colored metal rather than copper or silver, and based on the limited information I could find online, I thought gilding metal might be a less expensive alternative to gold. I ordered a sheet from the UK, but when I fired flux on a small piece of gilding metal, I found that it looked absolutely identical to copper after firing! The beautiful golden color disappeared completely, both under the enamel and on the rest of the piece. When I put it next to a copper disc I’d fired with flux and pickled, there was no difference in color.

Is this normal for gilding metal, or should it stay golden throughout firing? And if it should stay golden, am I doing something wrong or did I perhaps not receive the right metal? I’d appreciate any advice.

The stuff is 95% copper. It’s not going to be significantly different from pure copper as regards oxidation, reaction to fire, chemicals, etc. The only thing that is going to stay gold under vitreous enamel is gold.

Drat, I wish I’d realized that before ordering some gilding metal. Thank you so much for your help!

It’s my understanding that zinc is a nonstarter for enameling. Here in the states 14k yellow has trace amounts of zinc making it unsuitable for enameling and 18k yellow has to be used. The zinc is used like a flux to help in casting and most is burned off in the casting, leaving just a trace amount, but enough to interact with the enameling process. My guess is that when you heated up the gilded metal, the zinc burned off leaving just the copper. The Melting point of zinc is: 787.2°F (419.5°C). I don’t do enameling, so I could have it all wrong, but that’s what I remember hearing a long time ago, when I thought about do some enameling.

I would suggest gold foil as a more economical choice. Check out Enamel Art Supply. They have a variety of silver and gold fouls that are appropriate for enameling. https://www.enamelartsupply.com/foils

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Here is what I know based upon my researching enameling. This information comes from Linda Darty’s book on enameling, The Art of Enameling Techniques, Projects, Inspirations (pg. 20). This is not a direct quote, but contains the gist of what she is saying on this page in her book. I highly recommend this book to anyone interested in getting started with enameling. I have used it for years when teaching my students in the metal arts studio.

Metal alloys containing zinc can cause the enamel to pit or discolor with multiple firings. She recommends the following metals for enameling projects: copper, fine and sterling silver, gold (she does not stipulate karat quality) and pure gold, iron and steel.

Another factor she mentions in this same section is the expansion coefficient of the enamel as it relates to the expansion of the metal. Since both the metal and the enamel will expand during firing of the project, if the enamel’s coefficient of expansion is not lower than that of the metal, the enamel can crack or flake off the metal.

From personal experience I have had good results torch firing and kiln firing enamel on sterling and fine silver as well as copper. I have had fair results (at best) fusing glass to brass sheet, and poor results trying to bond glass to nickle sheet. I believe it is because of two factors: the expansion coefficient issue, and the zinc content of both of these alloys. When zinc is heated it “cooks off” (my highly technical term :slight_smile: ) and interacts with oxygen to create zinc oxide - a white powdery substance - on the surface of the metal. Enamel doesn’t like to interact with anything other than itself and the metal it is bonding to, therefore the zinc oxide causes pitting and/or a poor or very poor bond to the metal surface if zinc oxide is present. The nickle sheet I used contained about 17% zinc, and the yellow brass about 9-12% zinc. When trying to bond the enamel to brass it appeared to work, but as piece cooled many times - but not in all cases - the enamel would crack and flake off. This result makes me think that the enamel not sticking had more to do with the expansion coefficient than the zinc content.

I have never used gilding metal for enameling, but when firing copper using transparent enamel I have see the same result you got. It is the result of the copper oxidizing under the enamel and showing through the glass. I taught my students to use only opaque enamels on copper for this reason and save using transparent glass for firing silver work.

Hope this helps. Mike

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Ah, that makes sense. I’m new to all this and didn’t even think to consider that the zinc might burn off. Thanks for your help!

Thank you, I’ll look into that!

Thanks so much for all the fantastic information! I’m definitely going to get that book. I think my big error here was not considering that zinc “cooks off,” as you put it. :slight_smile:

Personally, I quite like the look of transparent enamel over copper (I tend to go for deeper, richer colors), so I think I’ll stick to that for now. Thanks again for your response!

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