Many summers ago I met an interesting looking lady at an art fair. She wore lots of jewelry, I mean a ring on every finger. The thing was, it was all copper jewelry! She bought, guess what, copper rings from me (see picture).
I asked her whether she ever got green stained fingers and she said “never”! She reminded me of all the healing powers of copper, the supposed anti-inflammatory action for arthritis and much more. Yes, I know, the internet is full of copper talk on subjects like “Copper Energy”.
But is any of this true? And why do some people apparently get green fingers and others do not?
This post reports on some answers.
To my amazement I found that metallic copper (and other metals like nickel and even gold and platinum) are not inert when placed on the skin, as when wearing a ring. Copper corrodes and the result is a film of copper salts such as copper acetate, basic cupric acetate and copper carbonate, also called verdigris (from Vert de Grece) salts. These are what we know as patina on weathered copper pipes and roofs, or statues like Lady Liberty in New York Harbor. This process is accelerated mostly by water, oxygen and salt (NaCl) of which there is plenty in sea water.
So what about a copper ring on your finger? The skin of the hand is covered with acidic secretions from 2 sources: sweat from eccrine sweat glands (clammy hands), and sebum which comes from sebaceous glands and is an oily substance that keeps the skin impermeable and acts as a physical barrier for germs that might otherwise penetrate through the skin. While the pH (a measure of acidity) is neutral inside the body, at around pH 7, the pH on the skin is 4-6, or quite acidic. This kills germs, but also contributes to corrosion of metals! Many normally produced substances are weak acids and are found in sweat and in sebum: amino acids, lactate, pyruvate, butyrate, and acidic lipids such as fatty acids.
In a lab experiment, metallic copper was exposed to sweat for 24 hours: the concentration of copper salts in the sweat increased by 100 fold!
In another experiment researchers measured the loss of copper from bracelets worn by volunteers. The bracelets lost 0.1 to 0.8% of their weight over one month due to copper corrosion. It was interesting that there was variation among the volunteers suggesting that some people corrode copper much faster than others! Finally, a study from Scandinavia looked at people referred to as “rusters”, who were known to corrode copper at a fast rate. These would be people with very green looking fingers after wearing a copper ring! They wanted to find out what was the difference between the sweat of these people and normal controls. It wasn’t the amout of salt (NaCl) or the acidity, but rather the copious amounts of watery sweat they produced…that means they had more water on the skin surface! Sweaty palms I guess.
While the copper from your jewelry can be dissolved on the skin as described above, there is also evidence that it can be absorbed through the skin and enter the body.
Whether copper has beneficial (anti-inflammatory) effects in humans with arthritis is still debated. There is only one study that has shown such effects in rats.
Note that copper can be toxic for cells. The oxidation process apparently results in toxic molecules called free radicals. It is these free radicals that are thought to explain the contraceptive effect of the common copper IUD by killing sperm and inhibiting implantation! Who would have thought?
With all the copper that we are exposed to, as through copper pipes with hot water in them, copper cooking pots, copper coins, and copper in most metal alloys, including those used for dental fillings, I do not think you need to be worried about the small amounts that may come from a copper ring. If you are a “ruster” but insist on wearing copper, you can still treat the copper jewelry with Copper Shield, or a similar acrylic product. I have also used clear Lacquer spray #2105 from Nikolas, although it smells terrible when you apply it! Any of these create a thin film that will insulate the copper from exposure to water, salt and oxygen and thus prevents corrosion, tarnish or verdigris.
My friend and teacher, Honey Jeanne Laber, has taught me how to use a flame (acetylene torch) and ‘color’ copper to get red, brown and even blue tones. You want to do this on a finished product. You can no longer buff the metal or shine it in any way or you will lose the tarnish effect. To preserve this finish use bees wax! You have to heat it up, for example in a hot water bath. Then you can use a rag, dip it in the wax and apply generously. Then you have to rub with your rag. It takes quite a bit of rubbing. The final result is a shiny finish with a protected varnish and color. A ring treated in this way does NOT tarnish your fingers!
I would love to hear your thoughts on copper jewelry.
- A short History of Sweat Gland Biology by K Wilke et al. In International Journal of Cosmetic Science Vol 29, pages 169-179, 2007.
- Corrosion Chemistry of Copper: Formation of Potentially Skin Diffusible Compounds by JJ Hostynek. Exogenous Dermatology, Vol 3, pages 263-269, 2004
- ‘Rusters’. The corrosive action of palmar sweat: II. Physical and chemical factors in palmar hyperhidrosis by O. Jensen & E. Nielsen. Acta Derm Venereol. Vol 59, pages 139-43, 1979.
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Very interesting… I make copper jewelry so this is good to know and be able to pass on to my customers! Thanks!
Hey Jess, your copper jewelry is beautiful – the patinas on copper are always great fun. Do you treat your finished products with oil, butcher wax or something like that? Thanks for you comment.
Thanks, Jess. You provide first hand feedback. 🙂
This post was very interesting David! I am currently obsessed with copper jewelry and have a stack of raw, untreated copper bracelets that I am wearing constantly…no green skin though. I guess I’m one of the lucky ones :-}
Thanks for your comment Kaitlyn. A bracelet is probably not exposed to as much sweat and skin grease, compared with a ring! I am glad that copper works for you. Perhaps I need to make a bunch of copper bracelets too? I love the copper look. It is a good looking metal. Take care, David
So if you use Copper Shield the natural patina process ceases and this keeps copper from leaving the green on the skin or rubbing off on clothing, such as a pendant onto a blouse?
Yes. That is the idea. Although you may have to keep applying Copper Shield at regular intervals.
What a great post! Thank you for sharing and I am so happy I stumbled upon it. I make copper jewelry as well, and frequently find myself not knowing what to say when doing shows and asked “won’t it turn my skin green?” I feel much more informed now, thank you. Also, I was working with copper and the torch heavily for a while, and began to feel quite sick. I believe that the fumes made me ill, as I was not wearing a mask and soldering daily (stupid). I am scared to pick up my torch again, which is a sad thing. Your blog has inspired me to pick it back up and to do it correctly this time around 🙂 Thanks again. I just started my blog yesterday (pretty empty so far, but more to come!) http://heatherkmurdock.wordpress.com/
You can get sick from the fumes of soldering due to a) the flux and b) lead contained within the silver solder as a filler metal. Check out this site.
This is such a useful article I also sell copper bracelets so very informative for me, thanks for sharing!