What is best way to clean and preserve copper coins?

[Carlitosway2]

What is the best way to preserve coins? I use to soak in olive oil if they started to flake before I got them home and it helps sometimes to see dates and detail better but now I just lightly brush in field and left over dirt shows what I think is just as nice details. Any better suggestions?

 

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[CRUSADER]

Peroxide bath.

 

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[Carlitosway2]

I have tried the Renaissance wax like copperstax said on buttons with very little success, It gets a residue build up along edges of details and still get that flaking.

 

[Lunch Bag]

Many indicate that water can damage metal objects, but weren’t those same objects subjected to water via rain sometimes for centuries? I’m trying to learn and would greatly appreciate an explanation.

 

[Carlitosway2]

Many indicate that water can damage metal objects, but weren’t those same objects subjected to water via rain sometimes for centuries? I’m trying to learn and would greatly appreciate an explanation.

this is where I have been noticing a problem with my finds. They come out damp and my problem is when they start to dry they become very fragile.

 

[MadTom]

Warm soapy water and your wifes or least favorite kids toothbrush.

Ha ha ha ha

 

[Silver Tree Chaser]

I believe that mineral oil is far better than olive oil. Olive oil is dark so it will darken a coin; it also has an acidic quality. Mineral oil is clear and has no acidity.

 

[huntsman53]

I believe that mineral oil is far better than olive oil. Olive oil is dark so it will darken a coin; it also has an acidic quality. Mineral oil is clear and has no acidity.

I agree but the acidity of the Olive Oil helps loosen encrustations, dirt and grime. You just can't leave a coin soaking in it for too long of a period. If only soaked for a week or so, it seems that Extra Virgin Olive Oil in most cases, does not adversely effect the color nor the condition of the Copper. That might not hold true if coin has been contaminated by some other type of acid or substance that can be harmful to the Copper. For this reason, it is often best to dip dug Copper coins in Acetone to arrest any verdigris, acids or other harmful substances. Once done, rinse the coin quickly, pat dry, then place it in the Extra Virgin Olive Oil or Mineral Oil.

 

[Aureus]

I have never seen peroxide damage the coins. I've used it on all types of copper and alloy, from Romans,fur trade rings to large cents. I usually soak the coin for 10 min or so and let it dry up (it turns the clay and mud into the fine dust which is way easier to remove),I repeat the process 3-4 times or as needed. Than, depending on the coin condition, cover it with a very thin layer of Renaissance.
The peroxide should be room temperature in my view, microwaved solution seems to be too agressive on the copper.

I personally don't see any reasons to soak the coin in olive oil but the soil conditions in your area might be different from mines.

 

[sprailroad]

Last week I did try the Hydrogen Peroxide on a few wheats just to see, and they came out spotted and rather ugly. I did microwave the Peroxide at first, and perhaps left them in the stuff too long? I'll try it again as Aureus stated, see what happens.

 

[Ahab8]

I'm still in the experimental stage as I don't find these coins very frequently and they are almost always pretty beat up. I've soaked coins in olive oil: I can't say I've seen too much change. I think you need to do it for months to really get results. I've used a stiff brush and a toothpick: sometimes it can improve the coin, other times it completely destroys the detail that is left. The line between dirt, patina and coin is pretty thin sometimes. I recently tried the microwaved peroxide method: It seemed to help on a coin that was probably going to flake and lose all detail. It's pretty amazing even after the peroxide cools down the coin will bubble for days (which is the peroxide working on the dirt) I've also seen large coppers tumbled and details that could barely be seen become a little more pronounced. I am going to go with peroxide and tooth pick for the time being. I'd like to tumble a couple of my coins. It's super frustrating when you have a coin that has detail but has a caked layer of dirt on it. When you scrape the dirt off you are left with less detail. I'm sure you are aware but most of these methods are irreversible. I wish there was one surefire method to get a coin back to it's former glory. Good luck! In your case it looks like those coins still have a lot of detail so that is working in your favor. I'd say just don't get too aggressive trying to get all dirt off if it looks like the details will come with it. Also as a final treatment you can put Renaissance wax on a coin. It will kind of seal it up and stabilize it from what I understand. All that being said I have a long way to go on coin conservation! haha.

It’s a delicate dance as we all know. I’ve had the luxury of cleaning at least 200 early coppers and I finally landed on cold peroxide in most cases. Some coins I have left in there for weeks. If you’re an impatient person this method is going to be tough for you. But it’s much more gentle than warm peroxide and the results for me have been far better. I will try to find some pics today. You will need to change out the peroxide every 2-3 days and you can inspect the progress when this is done.

 

[huntsman53]

I have bathed Copper coins in Peroxide on quite a few occasions and I just never had very good results. I also give fair warning that if you leave them in Peroxide too long, it will strip any and all patina from the coin, turn them to the pink Copper look we cringe at and will actually pit the metal. Other contaminants left on the Copper coin when it goes into the Peroxide bath, likely contribute to the results, so if hell bent on using Peroxide, I recommend a quick bath in Acetone and rinse with water in hopes of arresting and/or removing these other contaminants.

 

[Ahab8]

I have bathed Copper coins in Peroxide on quite a few occasions and I just never had very good results. I also give fair warning that if you leave them in Peroxide too long, it will strip any and all patina from the coin, turn them to the pink Copper look we cringe at and will actually pit the metal. Other contaminants left on the Copper coin when it goes into the Peroxide bath, likely contribute to the results, so if hell bent on using Peroxide, I recommend a quick bath in Acetone and rinse with water in hopes of arresting and/or removing these other contaminants.

Hey Huntsman, just out of curiosity did you use heated peroxide or cold? The only time I’ve ruined coppers with hp is when I used to use it heated up.
The problem with the questions is that there’s just too many variables. Our soil conditions vary so much from one region to the next. I’m always amazed to see how coppers come out of different areas. Some have a nice green color and some are more chocolate. All of these variables play a huge role in cleaning and preservation. I live in midcoast Maine and some of my coppers come out with a thick “coast crust”. HP is the only thing I’ve ever found that will slowly remove that very hard crust.
I guess my point is that there’s not going to be one right or wrong answer to these cleaning/preservation questions. There’s just too many variable. Hell I see a ton of different conditions in my own small area here. One thing I can say is that I don’t hunt old fields that have been fertilized for decades. So I have no experience with trying to clean those babies. I respect everybody’s experience and opinions on here. Lots of folks with a ton of knowledge. At the end of the day everybody needs to find what works best for their conditions....trust me I’ve destroyed a lot of coins attempting to figure it out.

 

[Aureus]

I have bathed Copper coins in Peroxide on quite a few occasions and I just never had very good results. I also give fair warning that if you leave them in Peroxide too long, it will strip any and all patina from the coin, turn them to the pink Copper look we cringe at and will actually pit the metal. Other contaminants left on the Copper coin when it goes into the Peroxide bath, likely contribute to the results, so if hell bent on using Peroxide, I recommend a quick bath in Acetone and rinse with water in hopes of arresting and/or removing these other contaminants.

I have never seen peroxide damage the patina, it does darken it a bit but I actually prefer it this way. I used it on coins found in all types of grounds and believe that if the coin comes out pitted it was done by the fertilizers or soil acidity way before it was cleaned. One thing I do before putting it in the solution is dry it for a few hours as I believe it helps stabilize the patina.
And of course, always use the cold peroxide.

 

[tomhighland]

DON'T! Let them dry and toothpick the loose soil off. That's it. All of the other methods will alter and devalue your coin. Check auction sites and you will find the value is decreased every time by " improper cleaning".

 

[huntsman53]

Hey Huntsman, just out of curiosity did you use heated peroxide or cold? The only time I’ve ruined coppers with hp is when I used to use it heated up.
The problem with the questions is that there’s just too many variables. Our soil conditions vary so much from one region to the next. I’m always amazed to see how coppers come out of different areas. Some have a nice green color and some are more chocolate. All of these variables play a huge role in cleaning and preservation. I live in midcoast Maine and some of my coppers come out with a thick “coast crust”. HP is the only thing I’ve ever found that will slowly remove that very hard crust.
I guess my point is that there’s not going to be one right or wrong answer to these cleaning/preservation questions. There’s just too many variable. Hell I see a ton of different conditions in my own small area here. One thing I can say is that I don’t hunt old fields that have been fertilized for decades. So I have no experience with trying to clean those babies. I respect everybody’s experience and opinions on here. Lots of folks with a ton of knowledge. At the end of the day everybody needs to find what works best for their conditions....trust me I’ve destroyed a lot of coins attempting to figure it out.

I have tried it cold, warm and hot and learned a long time ago to not leave Copper coins in Peroxide for an extended period of time. I placed an 1888 Indian Cent in Peroxide in hopes that it would clean it enough and reveal what I believe was the 1888/7 Overdate. Well things came up and because I got sidetracked, I forgot and left the coin in the Peroxide for a week. When I finally remembered it, there wasn't much left and the Date was obliterated. I know what you mean about soil contents and contaminants can really effect the results of Peroxide and a lot of other things used to clean coins as well. That is why I recommend a quick Acetone bath and rinse with water in hope of arresting and/or removing any contaminants before trying any method to clean coins. However, if a coin's metal has been permeated by some contaminants, it is likely that even Acetone and a rinse will help. It is possible that you could place the coin in Distilled Water for several weeks to a month or more, making sure to change the Distilled Water every few days in hopes of leaching out the contaminants. This would similar to leaching Salt out of items recovered from shipwrecks where the items are immersed in water for months and sometimes even years to get all the Salt leached out.

 

[huntsman53]

DON'T! Let them dry and toothpick the loose soil off. That's it. All of the other methods will alter and devalue your coin. Check auction sites and you will find the value is decreased every time by " improper cleaning".

In reality, any type of cleaning of coins is technically improper cleaning unless of course done by a Professional Service such as PCGS' and NGC's Conservation Services.

 

[Ahab8]

DON'T! Let them dry and toothpick the loose soil off. That's it. All of the other methods will alter and devalue your coin. Check auction sites and you will find the value is decreased every time by " improper cleaning".

No such thing as “loose soil” on the coins I pull out here in midcoast Maine. It’s basically a concrete crust that takes days of soaking to remove. For me personally I care zero about value or auction prices or labels from grading companies. It’s only about the history and eye appeal in my displays. I think if people are pulling coppers out of the dirt in hopes of making great profit 99.9% are going to be extremely disappointed. Of course we all need to use common sense and obviously if a very rare or valuable coin happens to be under your coil you treat it differently. I found a 1652 pine tree Shilling and threw it in a bowl of lemon juice because it’s a display coin for me even though it has decent value. I made sure to be careful to keep the dark toning and I only used a very soft mascara brush to remove the loosened dirt. If i was to find a NE Shilling that would change things of course. I suppose it’s different for everybody. What’s the threshold that people consider “valuable”. For me personally it would have to be worth more than $10,000. Even at that point it would depend what it was. I do this because I love history and the story that these coins and relics tell. I love to look at them in displays. It would take a lot for me to part with anything. If it’s a NE Shilling worth 6 figures that would be a different story. If it’s a modern piece of gold I could part with it in a heartbeat. Everybody needs to understand why they detect and what they’re trying to get out of it. That will guide you in your decision making processes

 

[flyadive]

A Must Read, Need I Say more....

http://nautarch.tamu.edu/CRL/conservationmanual/File9.htm

 

[Tommybuckets]

I have a large stack of barely discernible coppers. The dry rub in the field is the least damaging. I've never had any luck with water, hydrogen peroxide, electrolysis, lemon juice etc etc. A gentle but thorough rub in the field while moist is the way. If its just a copper disc its worthless anyway. I found at least 20 18th and 19th century discs this year and its a bummer. After a wipe in the field reveals nothing I toothpick or toothbrush it. Still nothing I run it under water to make t look hideous and relieve my curiosity. Then i throw it in the cup of despair with all the other ruined coppers.
Olive oil is ok but def will darken the coin.
Oxygen (and moisture) is the enemy to old coppers. To keep any air off the coin and therefore stopping oxidization, seal it in renaissance wax or I use an imperceptible layer of Vaseline. Vaseline is not water based so it does not have a ph and has no ill effect on metal. It could cause a buyer to turn it down since it has something weird on it. By keeping air from oxidizing the coin it helps preserve it. In my experience the detail is either there, or more often its not and there's nothing you can do to improve it but you can definitely help ruin it lol. The only decent one I found this year was a New Jersey state copper and Dfallis field wiped it for me since I didn't have my glasses and it has not been touched or cleaned since.
It sounds like the British soil takes more kindly to the peroxide method. The heavy fertilizer burns the coins up in my farm fields. Yards and woods they come out ok.

 

[BuckleBoy]

Warm soapy water and your wifes or least favorite kids toothbrush.

Actually, probably not the best. A wipe in the field will often help. Many use the peroxide and microcrystalline wax process.