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 Replies: 8 / Views: 3,941 |
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Valued Member
Australia
295 Posts |
Quote:
Hi all, I did an online search about coin cleaning and found an article about using hydrochloric acid to remove verdigris. (see posts below below - re not being hydrochloric acid after all) However, I worried about how this would effect a coin's value. So I did a quick search on this forum about using hydrochoric acid and how that would effect a coin's value - but couldn't find anything. I looked it up on the internet too, but again, I couldn't find a quick answer about whether or not it would effect a coin's value. According to the recipe I found online (60ml vinegar and 1g salt) I made up a batch and dropped in some coins for a few minutes and bingo - verdigris removed with just a minor discolouration left behind. I have to say the effect was much better than the verdigris. Seeing as how verdigris kills the coin's value anyway, I can't help but see how using this process would actually preserve the coin and prevent further rot, and by default, maybe preserve the value a little bit as well? Any thoughts or opinions or experiences to share?  Edited by awildeheart
11/17/2013 08:59 am
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Pillar of the Community
United States
2368 Posts |
*cringe*  All I can say is, I'm glad you're using acetic acid as opposed to hydrochloric acid. However, they are both pretty bad ideas. There wouldn't be much of a coin left... |
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Valued Member
 Australia
295 Posts |
Double I can't believe I didn't double check what I read on the internet before posting ... of course vinegar and salt isn't hydrochloric acid ... ... but it did remove the verdigris like it said it would ... |
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Pillar of the Community
Australia
4411 Posts |
Dont dont dont dont do it
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Valued Member
Australia
295 Posts |
Cries of shock and horror noted! But, everyone, please realise that I didn't suggest using this method on valuable coins - only coins that were already degraded in value or worth because of existing verdigris.  |
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Pillar of the Community
United States
1511 Posts |
Or you could use VerdiCare..... Invented and made/sold by our member BadThad... That's completely harmless to the coins...
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Pillar of the Community
United States
2368 Posts |
Good thing you changed that title, I almost had a heart attack when I read it! |
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Moderator
 Australia
16827 Posts |
I well recall back in the days of my youth, seeing the salt'n'vinegar treatment being promoted on a kids science TV show as a way to brighten up your dirty bronze coins. Clearly, this was back in the 1980s when one could still get bronze coins in change in Australia.
Being both a budding scientist and budding numismatist, I decided to give it a go on one of my brother's coins which I thought could use a bit of a clean-up. Unfortunately, either the show (or my inattention) failed to make note of the need to wash and rinse the acid off thoroughly. Needless to say, my brother was not impressed with the moonscape his coin became after having acidic residue left upon it overnight.
Hydrochloric acid (sometimes still known by its archaic name, "muriatic acid") is a much stronger acid than vinegar. It will remove verdigris, sure. It will also remove patina/toning and attack the metal surface directly. Pure acetic acid (concentrated vinegar) will do the same. The salt in the salt'n'vinegar mix is intended to buffer the solution and minimize attack of the raw metal; the metal will still be attacked, only much more slowly.
In short, there are much safer ways of treating and removing verdigris that do not attack the surviving patina and underlying metal anywhere near as severely as acids. Personally, I've had moderate success with neutral-buffered chelating agents (disodium EDTA) and strong alkalis (concentrated ammonia and sodium hydroxide). These all leave behind a coin that has been obviously "cleaned", but not a coin that has been acid-dipped.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis
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Pillar of the Community
Canada
726 Posts |
I have done a similar tratment as yours --Just the vinegar,,,no salt.....I am a believer........Note though that after finished (3 days or more submerged in vinegar)I put olive oil on the coins.......and I have only tryed it with coins of little value (buffalo 5 c that were in tough shape)...I too say the coin was more readable after the treatment.....then olive oil.. them wrap in 2X2 holders.....As I said if yu leave these coins alone yu don't have much of a coin....so then why not try something? I found that even after week under the household vinegar on some coins not much of an approvement...stayed a lousey coin......
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Replies: 8 / Views: 3,941 |
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Posted 11/17/2013 08:57 am
