Conservation for large cent

[simonm]

Hi guys,

I'm trying to conserve this large cent. It has some ugly green spots on the obverse. A few treatments of verdi-care and some picking with a toothpick have not done much to improve it. Do you recommend anything in particular, or is this coin beyond saving?

[Maineman750]

Have you tried a long soak in Verdi-Care ?
I also have heard it is pretty common to soak these old cents in mineral oil....but I don't know the details.

[simonm]

Have you tried a long soak in Verdi-Care ?
I also have heard it is pretty common to soak these old cents in mineral oil....but I don't know the details.

I did not fully submerge the coin in verdi-care, but I left some drops to treat the visible areas for about 24 hours with not much of a noticeable improvement.

[BadThad]

Personally, I would left it like it is. The verdigris is heavy and the surfaces underneath will not be attractive. I have removed this type of verdigris using acid (carefully) as I found that is the only way. Unfortunately, I found rather deep pits and the acid left those areas bright and shiny.

Coins that have had the verdigris advance to this stage are essentially goners. The best thing you can do is use VC, let it dry and then put it into an airtite. As they say "it is what it is".

[BadThad]

Have you tried a long soak in Verdi-Care ?
I also have heard it is pretty common to soak these old cents in mineral oil....but I don't know the details.

Mineral oil will not remove verdigris since it (verdigris) is a salt. Verdigris is insoluble in all aliphatic solvents. The old "like dissolves like" principal. It would be akin to using turpentine to remove a salt film that has dried on the metal surface, it ain't gonna work. LOL

The reason people use oil is the make the coin appear nicer since oil will artificially bring out the details, just like if you put water one a coin....yea, it looks better.... until it's gone....oil just lasts longer. However, oil will help prevent corrosion, but that will diminish with time as the oil evaporates and "runs off". It's not actually adhered to the coin, it's just sitting on it and eventually thin spots will develop and allow the corrosive process to continue.

One of VC's tricks is that it forms a polymeric layer as it dries. While it can be easily removed, it actually adheres to the surface and mildly cross-links to form a barrier. Combined with the ReAcT2™, it will offer excellent, chemical corrosion resistance over the long-term.

[admrose]

I'd leave it. It'll still fetch a good price.

[simonm]

Personally, I would left it like it is. The verdigris is heavy and the surfaces underneath will not be attractive. I have removed this type of verdigris using acid (carefully) as I found that is the only way. Unfortunately, I found rather deep pits and the acid left those areas bright and shiny.

Coins that have had the verdigris advance to this stage are essentially goners. The best thing you can do is use VC, let it dry and then put it into an airtite. As they say "it is what it is".

Thanks Thad. I'll give it one more treatment and then put it in a flip or something to protect it.

[Gunnovice09]

Can verdigris spread from one coin to others?

[GrumpyEd]

However, oil will help prevent corrosion, but that will diminish with time as the oil evaporates and "runs off".

For that reason I would soak it in mineral oil, maybe repeat it every few years. It's not going to reverse the damage but it will slow down any new corrosion.

[BadThad]

Can verdigris spread from one coin to others?

YES! I call it "contact corrosion". Verdigris needs feed materials to grow and it can actually supply feed materials to other coins. Keep all coins with verdigris isolated.

[Gunnovice09]

Thanks for the info badthad!

[Gunnovice09]

Probably a dumb question but what exactly is verdigris?

[BadThad]

Probably a dumb question but what exactly is verdigris?

This is from my book, I also added it to Wikipedia:

Verdigris is a variable chemical mixture of compounds, complexes and water. The primary components are copper salts of acetate, carbonate, chloride, formate, hydroxide and sulfate. The secondary components are other metallic salts, acids (organic and mineral), atmospheric gases and water. All the components are in an ever-changing and extremely sophisticated electrochemical reaction equilibrium that is dependent on the ambient environment.

[Arjohn]

Think of it as Rust for copper/bronze

[Gunnovice09]

Thanks guys!