My goal isn't to clean/alter the coin itself but just remove particulates that are not a part of the coin (conserve / restore). I understand that it won't make the coin inherently more valuable. However, for some coins that may have PVC haze or foreign material buildup that are obscuring the view of it. I'm trying to test out this process to see what it can remove to make the full true condition of the coin visible, which hopefully would show it is in better condition than it looks (though could also reveal flaws). Also I want to see if it does make any color changes or alters the coin itself. I thought I would just share my outcomes in a thread for the benefit of all. I started out with some modern junk zinc pennies that are pretty obscured (not fully sure what is part of the coin and what is not). I should have re-taken pictures before to keep the lighting consistent so they may be some color changes due to that. I'll take before pictures next time. I meant to leave them in the acetone for 24 hours and flip them about 12 hours in. I did that but also life happened and I didn't get a chance to get them out last night so the reverses got an extra ~12 hours. I soaked them for this long to give it what I thought would be an extreme to test if it had any adverse effects. 1989 Obverse Before: 1989 Obverse After: Looks like a little reduction in the white / green around the edge. The dark area isn't quite as dark. I see a slight lightening of the brown/orange coloring but again, that could be lighting differences. I think it very well may be that as the paper I have it on has a slightly different tint to it. 1989 Reverse Before: 1989 Reverse After: Again seeing a little reduction of the white in some areas (near the O in ONE) but not so much in other areas. Perhaps if I ran this cycle multiple times it would eventually remove it? 1989-D Obverse Before: 1989-D Obverse After Again maybe some slight reduction in the green. It still looks like it just has particulates sitting on top of the coin. I know better than to rub the coin but what about shooting it with compressed air to try to get the chunks off? 1989-D Reverse Before: 1989-D Reverse After: Similar result. I can can start to see the bottom of the Memorial building through the big white chunk at the lower right side of the base. Other white areas may be slightly reduced or the same.
I also threw in a copper penny: 1974-D Obverse Before: 1974-D Obverse After: I was wondering if it would reduce the spots. Maybe it did slightly but I'm not seeing much difference. It did lighten the haze around TRUST but also had some greenish color show up on IN GOD. 1974-D Reverse Before 1974-D Reverse After: The reverse seemed to lighten the dark spots more so, maybe because it was right-side up for longer... However I see a bunch of greenish hue in the Memorial now and that big spot above CENT now is greener. Looks like it may have uncovered some corrosion.
Yea, not a ton if difference. I do see slight lightening of the spots on the copper but maybe I need to refresh the acetone during the process.
Acetone will affect only certain kinds of surface deposits (mostly organic matter, greasy/tarry/plasticky stuff). Most of the white, green, and dark spots you'll see on Zincolns are metal oxides and other mineral stuff. As you've shown, acetone won't touch those. You could let the coins soak in the stuff for a century, and the deposits would still be there. Mild acids like vinegar will get rid of the deposits, but they'll ruin (further) the underlying coin as well. Don't ever do that to a coin that might be valuable, but feel free to try it on the coins you pictured; it will be educational.
Want to do a little experimenting? Try your tests using Hydrogen Peroxide. Pick it up at any grocery store or pharmacy.
Thanks for sharing this with us and showing pictures. Wonder how it would work with coin like a quarter, dime, or nickel.
Agreed but identifying what "gunk" is organic and what is not is also part of what I'm learning so I can determine which coins it makes sense to soak.
A good learning process then. If you stand the coin on its edge leaning against the glass side, you don´t need to worry about having eneven coverage. Also, 10-20 minutes is generally more than enough for organics. Good luck
Reading the title... Experimenting with I envisioned a glass beaker on a hot plate with the rotating object being spun around in magnetic stir pills. (PSA) Don't heat acetone.
Good news - the white/green stuff is inorganic salts that have some solubility in water, try that... Bad news - the white/green stuff means there was damage to the zinc under the copper coating and that can't be reversed. Suggestion - try warm water in a WaterPic.
