Any solutions to clean old bronze medal?
Samuel8
Posts: 380 ✭✭✭
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Samuel8
Posts: 380 ✭✭✭
Samuel8
Posts: 380 ✭✭✭
Comments
Much depends on what type of contamination is on the medal. For example, glue, paint, tarnish, verdigris or cat barf. Any further information or pictures? Cheers, RickO
Photos needed.
This is the picture. The dirty stuff on the medal is black, sticky, oil-like.
I saw some medals from dealers are very clean, and also look like they apply a layer of oil or something.
I bought some medals were very clean, I can tell they were cleaned.
I also checked the NGC service, it is not very clear on their website.
I am thinking to clean the medals myself.
Thanks for your advice.
See photo.
@Samuel8 .... Begin with an acetone soak...Get pure acetone. Likely for a few hours, keep the glass container covered with a glass cover (it evaporates quickly). Acetone will remove organic substances and not harm the metal. Rinse with alcohol then hot water. It should work... Let me know. Cheers, RickO
I'm not sure that is not the original finish. I wouldn't touch it. Many large medals are patinated as a part of the manufacturing process.
I found this thing, what do you think about it?
https://www.wizardcoinsupply.com/lindner-coin-cleaning-dip-copper-nickel
This definitely is not the original finish, I can feel it is very oily, sticky and not stable.
@Samuel8 ... I would not use that product since it could harm the metal surface....It has HCL as a component. Stick with acetone. Cheers, RickO
Acid bad. If acetone does not alter the finish then leave it as is. Original patination comes in a variety of flavors. What's the date on this Austrian item? Peace Roy
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I am not sure about the date, probably around 100 years old.
since you're asking what to do I'll assume you are ignorant of what to do, what to use and how to preserve things when you're done.
for those reasons, I suggest you do nothing.
Yes， you are correct.
But I do have an urge to do it.
https://www.wikihow.com/Clean-Copper-Coins#:~:text=Copper coins often turn a,exposed to salt and water.
I tried the methods in the above link with some old dirty pennies (I tried to find similar condition pennies):
in the picture, the coins from left to right:
1. salt with the vinegar: most effective, but more erosive, surface color changed.
2. First oil then vinegar: not effective
3. First ketchup then vinegar: not effective
4. baking soda: somewhat effective
I think at this moment, I will try the vegetable oil first.
Yeah I too feel that medal has "pre-aged" factory applied patina and that was never bright to begin with.
But this medal is about 100 years old, people did that at that time?
Yeah it's something that was already done around the turn of the century as there's medals and tokens from around 1910-1930 that came pre-aged. Don't use salt, vinegar, ketchup, or baking soda on any coin as they are all either abrasive or acidic. Proper conservation takes time and patience just soaking in mineral oil. I've had heavily verdigris copper soak for close to 2 years and straight grade once done. I would also stay away from using acetone on brass.
I would leave it alone. Anything you do to it will make it less desirable.
Could you show a pic of the reverse of your Karl Goetz medal?
I want to see the reverse.
I might try just plain drop of mild dish soap and water, with distilled water rinse. No rubbing or scrubbing of any kind.
Best bet is to leave it alone, or you will probably damage it, and it looks pretty good to me as is. Part of the beauty is the good original, gnarly old medal look.
My US Mint Commemorative Medal Set
I found this picture online. Of course they are professionals.
I think these 2 medals should be the same thing beneath the dirty stuff.
How about leaving it alone and buy yourself a shinny new one. Have you ever heard of antique patina?
@Samuel8.... I guess you just will not try the one method that may help without damage (vinegar is acidic, salt will damage metal, ketchup? Going from the sublime to the ridiculous), Use acetone, 100% or just get rid of it and buy one you like. Cheers, RickO
With all due respect, don't touch, clean, or even look too hard at your coins/medals until you learn about them first.
Virtually everything artistic ever made from bronze received some kind of patina when made. It was not just for appearance but for protection of the surface.
In theory, a bath with a mild degreasing soap might be OK, but I'm not even sure I'd risk that. Acetone (pure) as recommended is about all you should be doing.
One other note.... I have some Chinese counterfeits of various silver coins and they are coated with a dirty and tacky substance to mimick tarnish. I am not saying your medal is fake, but that is one angle I might consider.
acetone ONLY first. then maybe mineral oil. but you have to rinse all this stuff off.
If the medal feels sticky, that is probably because it has PVC contamination on it from being is an old pliable PVC plastic "flip" holder. Like some others here, I would recommend a bath in some type of organic solvent (acetone, laquer thinner, or even "goo-gone"). Beyond that, there is nothing else that you should do except store it in a non-PVC holder.
The cleaner-looking example of the medal, shown earlier in this thread, may have already been improperly cleaned and might not correctly represent the original type of finish.
So, I cleaned it.
Yesterday, I left it soaked in vegetable oil overnight. This afternoon, I rubbed it in oil. Not so clean.
Then I used cotton ball socked with vinegar to rub it. I didn't want to soak it in vinegar to avoid damage to the surface.
After 2 cotton balls, I can see the difference. Then I used soap and water to wash it, I noticed the soap also worked very well. It cleaned the rim which was black before. After several cotton balls with soap it looks like this now. I am pretty satisfied with the result. The black stuff got cleaned and patina not damaged. Comparing to my other medals, the patina looks very similar to the most clean ones I have. The vinegar did corrode the surface a little bit. I can see the cotton ball turned green later.
Well, if you would use acetone you would be clean and no corrosion and no residue....but you choose to ignore the advice. Cheers, RickO
I know. But I do not want to go out to buy acetone, and want to use the thing I currently have in the house.
I would have tried acetone as recommended by very experienced people which is good for removing organics like oil and usually will not alter the medal, but even then some old bronzes had a lacquer coating, and the antique finish is there on purpose.
I liked the old grungy look because of the design, and I think it lost most the dark contrast that gave it definition after the vinegar wiping.
But, if you like it, that is all that really matters.
My US Mint Commemorative Medal Set
You went out and bought a dirty medal but aren't willing to invest in proper solvents? OK, that's your decision. But then why ask for advice?
In any case, I do not know anything about this medal, but I do notice that yours has surface bumps and "ghost" lettering that the online photo you posted does not have.
Unbelievable.....
Cheers, RickO
First off do not use vegetable oil only use heavy mineral oil. Even at this point after doing what you did if you want to keep the surfaces stable, you should go out and spend the 7 or 8 bucks and get acetone. Let is soak in acetone as Ricko recommended overnight. Then give it a light coating of the heavy mineral oil to preserve the surface.
By the way, why not show both sides - it seems like an interesting medal.
I appreciate all the advices you guys provided.
It is just I do not want to go out to buy acetone, and this medal is not an expensive one, so I want to give it a try with the items I currently have in the house.
After that, I read online for a couple of hours about acetone and coins.
People said acetone has no problem with silver or gold, but people are debating about acetone on copper coins. People have different experience with acetone on copper coins.
Below is something people posted:
https://www.stonybrook.edu/vescalab/research/research7.html