How to clean Chinese copper coins find

I am new here please how to clean Chinese old copper coins. I don't know of damaging or something I do wrong. Please advise. I attach the some of pictures.

Welcome to Numista!

I've heard of leaving copper coins in olive oil for a while, but I've never tried it so don't quote me on that. It's generally advised against cleaning coins as a rule, but if it's grit and dust we're talking about use a toothbrush; the fine bristles could remove bits of detritus in the details of the coin.

Anyway, for the last two coins they seem too damaged and worn already to bother with cleaning.

Quote: "CassTaylor"​ use a toothbrush;

Nah. Your first instinct was the correct one. Leave the toothbrush in the bathroom.

Olive oil is used mostly to soak encrusted coins freshly dug from the ground. I don't think even the most rigid purist has ever raised any objections to this practice. Other than that it's used in an attempt to recolor cleaned copper via prolonged soaking or to bathe coins prior to making an attempt to remove stubborn dirt. The jury is still firmly out on whether the former actually works. With verdigris and other forms of corrosion it's certainly better than nothing. It will both conceal the discoloration and arrest the spread. However it's a pretty heavy oil so it does have an unfortunate side effect. As it dries it combines with the contaminants on the coin's surface and airbourne to create an unpleasant thick sludge which will coagulate around, for example, the letters in the legend. It's not huge problem as the same thing occurs naturally during circulation to a much lesser degree.

You've probably noticed coins like this, with an especially "gunky" look. Well, that's probably olive oil. It's much better to use a lighter oil, the lighter the better. Some folks swear by WD 40 but I'd be hesitant to use something with so many additives plus propellant on a coin with any great value. Plus it has a distinctive smell which is quite persistent. I use Remington gun oil, which is actually cheaper than olive oil if you buy the 10 oz. bottle at Walmart - $6.77 + tax. It's made specifically to clean and protect metals. The surface of a coin has a great deal in common with the blued steel barrels of a well made gun but that's a subject for another time. For those living in parts of the world where there's no market for gun oil I'd recommend sewing machine oil which is pretty close.

Oh yeah, toothbrushes.... almost forgot about that. I've seen this suggestion repeated countless times so clearly there's a widespread belief that they're safe to use on coins. It's a pretty plausible sounding argument which goes, "If it's not damaging to my teeth then surely it won't harm hard metal coins." Well, not really. First of all tooth enamel is pretty hard, it's meant to last three score years and ten. A set of teeth made from softer metals such as copper or silver would be worn out in no time. Plus you're aiming for two different outcomes. A cleaned and polished set of teeth is a great thing, coins not so much. You just don't hear folks saying, "Never clean teeth!".

It's my belief that more coins have been ruined by toothbrushes than by any other tool. They're abrasive, that's how they work so they will inevitably score the coin's surface and it's a shotgun approach affecting a wide area beyond the bit of dirt you are trying to remove. A softened wooden toothpick will give much better results. You will have to soak the coin first though, in water, olive oil, liquid soap.... whatever you find works best for you.

For common, low value coins none of this really matters of course but I believe it's wise to get used to good habits right from the outset so you don't have to unlearn bad habits as you progress to more expensive coins.

Quote: "pnightingale"​

Quote: "CassTaylor"​ use a toothbrush;
​
​

​Nah. Your first instinct was the correct one. Leave the toothbrush in the bathroom.
​

​It's my belief that more coins have been ruined by toothbrushes than by any other tool. They're abrasive, that's how they work so they will inevitably score the coin's surface and it's a shotgun approach affecting a wide area beyond the bit of dirt you are trying to remove. A softened wooden toothpick will give much better results. You will have to soak the coin first though, in water, olive oil, liquid soap.... whatever you find works best for you.
​
​For common, low value coins none of this really matters of course but I believe it's wise to get used to good habits right from the outset so you don't have to unlearn bad habits as you progress to more expensive coins.
​
​
​

​Agreed on that, but I wasn't suggesting using a toothbrush to clean coins, rather to dislodge multiple large bits of grit in the devices (such as on coins found metal detecting).

Quote: "pnightingale"​
​
​Oh yeah, toothbrushes.... almost forgot about that. I've seen this suggestion repeated countless times so clearly there's a widespread belief that they're safe to use on coins. It's a pretty plausible sounding argument which goes, "If it's not damaging to my teeth then surely it won't harm hard metal coins." Well, not really. First of all tooth enamel is pretty hard, it's meant to last three score years and ten. A set of teeth made from softer metals such as copper or silver would be worn out in no time. Plus you're aiming for two different outcomes. A cleaned and polished set of teeth is a great thing, coins not so much. You just don't hear folks saying, "Never clean teeth!".
​
​It's my belief that more coins have been ruined by toothbrushes than by any other tool. They're abrasive, that's how they work so they will inevitably score the coin's surface and it's a shotgun approach affecting a wide area beyond the bit of dirt you are trying to remove. A softened wooden toothpick will give much better results. You will have to soak the coin first though, in water, olive oil, liquid soap.... whatever you find works best for you.
​
​

​And actually there's plenty of evidence that they do damage teeth as well! There's a big move on now to encourage people to use the softest brushes and brush for more time with less pressure. Be nice to your teeth and your coins!

My wife's younger sister now sports a set of very expensive dental implants due to her obsessive brushing. Her dentist, who I reckon would know about such things, placed the blame equally on the newer "whitening" toothpastes.

You can always buy another coin but if you bugger up your teeth it's game over.

I practice cleaning on corroded and stained US cents, US "nickels", and any "worthless" foreign coins I get which have corrosion. I never clean a coin worth anything over a few dollars. If these Chinese are unreadable, they may be "worthless" enough to clean. if the nice ones catalog at $10 or more, I would not clean them.

Quote: "uzegch"​I am new here please how to clean Chinese old copper coins. i dont know of damaging or something i do wrong. please advice. i attach the some of pictures.
​

​Hello uzegch and welcome to the world of Numista. As suggested by others, I would do little to nothing with the top three coins but the bottom two are showing slightly more advanced stages of verdigris or copper oxide corrosion. I have had some moderate success with using pure isopropyl alcohol (or rubbing alcohol) applied gently with a clean cotton bud and then rinsing off with some mild dishwashing detergent. Once you have gently padded them dry and stored in a holder or album away from any moisture source then you should be able to enjoy them for many years to come.

Hello folks thank you for replying on my post. I am first time to be cleaning coins I have . I will clean it then post it here again. I find gun oil and sewing machine oil and I have ms 70 and Iso-Propyl Alcohol. See you guys little bit later on...