Tarnished coin cleaning

[Goldseeker]

OK, Thanks trout.   Will give it a try.

I will take before and after photos of the coin(s) and post so all can see the result(s).

[qman69]

Does acetone cleaning affect coin values? Just curious as most everyone says "DO NOT CLEAN".. lol

[5 rubles]

I have run a small test; I took two identically PVC stained coins and soaked one in acetone for 24 hours at Sydney winter garage temperature, about 10-15 degrees C. That cleaned the coin quite a bit but not enough for my liking. I left that coin as a reference and left another similar coin in acetone now for 5 days. the result is remarkable. about 80% of the PVC stains are gone. so the coin goes back in the soak. I expect the coin to be almost mint in 2-5 days. I will post pictures once the experiment is finished.
To answer other posts asking how to stack the coins, I have a glass lunch box size container with alfoil cover topped with its original plastic lid for good seal. I stack the coins on the bottom so that first is flat against the bottom then the following coins are resting on the edge of the previous coin and so the coins circle around the container resting on each other. The contact area between each coin is very small so that causes no problems. I tilt the container from time to time to move the acetone without moving the coins. I use wooden chopstics to handle the coins.
To qman69, I do not clean circulated coins because that tan or patina is very valuable. I only soak mint coins stained by PVC covers. Also never put copper coins in acetone, it makes them purple in just few minutes. try that with an old one cent coin if you like to have a rare purple copper coin and sell it on ebay...LOL.

[qman69]

What does a pvc stained coin look like? Also I now have a heap of copper/bronze 1cent Straits Settlement coins...they are ranging from brown,red,streaky,green stuff etc. would be nice to clean them up if possible. They have had a hard life in a PVC coin album, and most likely have been sitting in that album for 30-40+years. I have given them a wash in warm soapy water with a quick rub with an old soft toothbrush.

[Fordprefect]

This use of Acetone does not cure all evils.
If it is taking multiple bath's to remove the PVC
it is most probable that the coin has sufferred surface damage.

1971 50c from Mint Set Wallet.



After three Baths



12 Months Later, Coin has Permanent Carbon Damage

[5 rubles]

PVC stain looks like a cloudy layer on a coin. if it is bad, it turns green, what i have read and feels sticky. soap and water is a very soft cleaner and does not remove pvc from affected coins. That green layer is an acid compound and should be cleaned otherwise it will eat the rest of the coin.
I hope experts here will also advice, i do not claim to be one.

Acetone will dissolve most plastics like PVC and anything organic, it is safe on most coins. The modern Australian Dollar and 20 cent coin cleans well and will not discolour, not sure about silver, i have not cleaned any. Copper, definitely not in acetone. I would be reluctant to put tooth paste on any coins.
Can you upload a picture here so others can advice.

[JeffH]

Toothpaste NO!
I have never had "coppers turn purple after prolonged soak on acetone. I always give them a rinse in water asap after removing them from the soak.
Have you been sold a bottle of  contaminated acetone?

When I give coins an initial soak in warm water I add a drop of detergent as a wetting agent. AlBr coins ($2 & $2) do not like most detergents -the colourful die plays havoc with them. I have found that window cleaner (blue), which seems to be alcohol based, is better.

[5 rubles]

Don't know about contamination JeffH, just regular Bunnings acetone. I read about it on internet and tried myself, and yes, purple it became.

[qman69]

lol... only warm soapy water and an old soft toothbrush..no toothpaste involved!

Here is a pic of the 1c coins..odd that there are so many different shades of colour.

[trout]

Those look really cool :good:

[5 rubles]

very impressive gman69, what a beautiful arrangement, that could be a design for a material or just a big picture on the wall. I would not clean them with anything, now they look like time has stopped and those coins have a long story to tell, so many hands and so many places they have been. What have they bought over their life time? amasing. Can you imagine the dna they have, like a bank vault of human history. just preserve them as well as you can making sure the green copper oxide does not spread.
This is the best "group photo" i have.

[robbiegal]

wow great collection qman

I have a small professional ultrasonic cleaner and have at time popped coins in it
I put the coins on a silicone mat in the machine
it loosens the grunge but doesn't really remove it, so I still have to rub the coin with a clothe anyways so I think it works similar to warm water and a toothbrush! and you safe a thousand bucks in the process!!

a bit of an oil type lubricant on those green sections might help to retard further growth especially if you have given the Verdi grise some water to react with

[JeffH]

I have a couple of ultrasonic cleaners I sometimes use with coins -didn't actually buy them for that.
I put a plastic food container in the cleaners -as large as will fit- I have cut some polycarbonate sheets to fit neatly in the containers and drilled a lot of small holes in them for good fluid circulation. Lay a sheet in and then a layer of coins, then another sheet, more coins and so on. Any more than four layers of coins seems ineffective.
I use water with a drop of detergent and it can become quite dirty. Cleaners can overheat if run continuously and recommended maximum 30 minutes on, 30 minutes off. I find at least four cycles of this is needed.
After removing the coins then a rinse in clean water and pat dry. Some come up very well and some still look the same. Sometimes I get a yellowish film on some coins; I think some contaminant on one of them is probably responsible. A quick clean with acetone usually removes that and then another go in the ultrasonic cleaner for them.
Any still dirty (and maybe worth keeping) I give a similar go in my smaller cleaner with water with a teaspoon of acetone added. That often does show significantly more improvement.

I stress that these are noodled, circulated coins only -that would otherwise go back to the pond- and would never do it with mint set coins

It's amazing how dirty the water becomes with a batch of old pennies or halfpennies. I don't think this procedure really gets them cleaner than a toothpick and acetone or xylene. But it is convenient just to press the timer button every now and then and walk away to do something else.

[robbiegal]

I think the yellowish film can also be from olive oil
I have heard that it can do that to coins and over the years it develops in a  hard film

[5 rubles]

Here is a sample of cleaning PVC damage with acetone. Both coins have been in a pvc containing album sheet without any other protection for about 14 years. The damage to both coins were identical. The "cloudy" coin has not been treated with anything. The damaged coins feel sticky to touch. 5 hours of acetone bath resulted in much improved look in the darker appearing coin which has much more shine and lustre now.