You don't want to etch away the underlying silver/copper, just de-oxidize it. People who do conservation for marine salvage and archaeology have lots of technical knowledge and skill on this topic, but I don't know how much is available for free.

At any rate, DO NOT apply any sort of solvent.

The baking soda/aluminum foil/hot water method is an electrolytic technique for silver only. But I would never try it on something old, would do my best to find a professional conservator first.

Jan,
A friend that conserved hundreds if not thousands of ancient coins told Suzi and I what we needed to do with very grungy metal. Bronze Copper and Silver.

Suzi and I have conserved more than a few old Byzantine and Roman coins with very good results. I have attached two images of an 850 year old Byzantine coin to show the results of this type of conservation.As you can see in the images the results can be amazing.

Make a saturated salt water solution, enough so you can hang your piece in it. Put the solution in a glass/plastic container. Wrap your piece in a few places with copper wire fine but not too fine, if you have three or four wires bring them together up top and twist them together a bit. Get an old piece of stainless steel and old butter knife will work.

Get yourself (thrift stores are great for this)an old wall plug transformer, most go from 120volt to either 9, 6, or 3 volt. The kind used for calculators and such. Get a three volt (the best)I would get a few if they have them.

Cut the plug that goes into the electronic item 3 volt output. Split the wires and put an alligator clip on each wire. Put one clip on the copper wire twist and the other on the stainless steel piece that are in your solution keep the stainless steel from touching the piece being worked on. Plug the transformer in and look in your solution if bubbles are coming off of the piece to be cleaned this is right if off the stainless switch the clips.

Depending on how much grung is on the piece will determine how long this process will take. We usually slowly spin the coin back and forth so the electricity is not a constant in one spot. Every once in awhile remove the piece and see if things are lifting, if so pick at them with a tooth pick to help in removal.

Might be best if you want to give me a call so I can make this a bit clearer. I assure you that this process works perfect and seeing as though it works at such a microscopic level on the metal you have little chance of causing damage to it.

All my best .......... Danny

contact me if you want my phone number.

Greetings, Jan. I think of you often and am so happy to see you posting. Happy Holidays!

If you take a look at Danny´s result. What a difference! Now it is possible to enjoy the original coins and images instead of just the form.

All the best,
Hendrik

Hi Jan,

It is an interesting piece and difficult dilemma.
I would sell it and pass the problem on to the buyer.
But first, I would commission an appropriate display stand.

The piece was made to be viewed without 1000+ years of corrosion - I would use Danny's expert advice and clean it so you can appreciate the artistry in its original form.

I think there is a wax that can be applied after cleaning to protect the surface and slow down the re-oxidation so that it doesn't blacken up in short order after the cleaning. I'm sure Danny can advise on this as well.

Never look in a full-length mirror.
And only use a mirror in soft light.

I took a lot of Asian art history classes in college, and there was one passionate professor who spent an entire class arguing the merits of cleaning vs. leaving a metal object in the state it was found, especially ancient bronzes.

Apparently, it's an age-old debate. There are those who believe the object should be restored to the artist's original 'vision' for the piece--to restore it to the state it was originally.

Then there are those who argue the artist knew patina would age the piece, and created it to become even more beautiful and worn with age. To clean up an object and restore it to its original state was to remove its history.

I think she said throughout history, one approach or the other would gain ascendancy.

When I lived in Michigan lo-these-many-years-ago, a friend took me for my first visit to the Detroit Institute of Art. There was a small bronze statue of a burro, almost hidden in the basement. My friend said when she was a kid, it used to be in the main entrance. Over the years, thousands of children would see the burro as soon as they entered, and rush to pat its back and ears and nose.

After decades of this touching, not only did the patina disappear, but the actual details in the burro's fur wore away. Where children had petted it was worn smooth and golden, in contrast to the dark patina and carved/molded details. To preserve it, it was moved to the basement where fewer children would see it.

She said she understood, but she felt an important period of her childhood was put in the basement, too. :^) And that petting the burro was part of a child's museum experience, and probably encouraged and enriched their experience with art.

I remember standing there looking at it, and I think I touched its ears and nose and back, too. I remember wishing I'd seen it as a child. In a way, I think this memory is one I've incorporated into my own artwork, making things that people are allowed to touch.

I think you know what you'd LIKE to do, and you are also concerned about doing "the right thing". I think the artifact is in your possession, and you should do whatever feels right for YOU. If it would bring you joy to see the original state or simply to clean it up so you can see ANYTHING, do it. If you feel it should stay in its current state, do nothing. As Danny said, you could start the cleaning process and stop when it's 'good enough' for you.

hth, and welcome back! We've missed you.
Luann