Green Copper Corrosion - Chemistry

Carl - No, I have not tried mineral spirits. I have tried other organic solvents like hexane, methylene chloride, toluene and xylene with no success. MS are just a hydrocarbon mixture, to be honest, I'm surprized it works at all. It must have some non-polar characteristics/compounds such as long-chain alcohols because verdigris deposits are polar in nature. The alcohols serve as very weak acids and likely exchange the acetate anion to form acetic acid.

Repeat of 96-166 test with coin from Arthrene. This is an ugly coin, I suspect the corrosion has eaten into the surface. I can't wait to see what happens:

Initial

Now that is a test coin! Good sample, Arthrene!

I cannot wait to see how it turns out!

There's a coin somewhere underneath all that!
Your formula is sure going to be busy.

JustCarl......


Carl.....
When you want to "reply to a topic" you need to click on "reply to topic" at the bottom of the page, but above where you usually start typing. Not the usual "quick reply" area. You'll see "New Topic", and "New Poll" and then "Reply to Topic". Go there. Once you click on that, a new page will come up with a blank place for you to begin typing. Look at the "Format" area above this where it lets you change the type to "bold", or "Italics" or "Underline" ect....The second one from the right side is an icon that looks like a little piece of paper with a red arrow on it's right side.....that is the icon to click on to make "quotes". You first, though, find the quote you want, click copy, then "reply to topic", then click that icon for "insert quote".. go to where you should start typing and click again there. It will insert the quotations you've been seeking right there (paste your qoute in between the quotations) and there ya go !......hope that helps...i was irritated until I figured that out too !...

Carl....Since I can't partake in a "Chemistry" discussion intelligently.....I'm glad to offer this help at least !...

Hey so if a "method" is figured out......are ya'll going to bottle this and sell it to us in the coin collecting community ?......and can I buy into the company that'll be selling this soon ?....I WANT IN !

This is one tuff nut to crack! I'm glad Arthene sent me a few like this, it's the ultimate test.

Initial



After 24 hours



Close up initial



Close up 24 hours

Eagle - I don't think I'm there yet and this was never intended for severe applications. I'm thinking of not testing any more of these extreme cases and going back to coins with lighter verdigris. I can always work on a "heavy-duty" formula later.

Nonetheless, this current coin has been an interesting experiment for me. I finally have a bit of time to work on this again! I did manage to change out the fluid everyday on this coin. Just no time lately to take pics.

Initial



After 4 days



Close up initial



Close up after 4 days



4 Day Summary

I'm actually quite surprized at the success! The forumla I'm using is quite weak for corrosion this severe. When I developed it, the intent was to save a good coin with light verdigris. I suspect I could increase the concentration by 10-100 fold and have pretty decent results on coins like this one.

The coins details are actually coming out. You can clearly see the mint mark now and the portrait is starting to show hidden detail. It seems that mostly the difficult to remove copper carbonate is remaining. If I ever get some time, I want to confirm that the white material I'm seeing left behind is actually carbonate. Perhaps a drop of a weak nitric acid solution will confirm carbonate (produces gas bubbles of CO2). At the end of this test, I'll toss a drop on to see what the effect is.

I believe most people trying to conserve a coin this bad would simply acid dip it because the patina is likely already ruined.

I made a joke on here and I just realized it might of been a little offensive and for that I apologize. I wasnt thinking.