Verdigris on higher grade coins

[JobIII]

Hi all,

I have been storing pennies in 2x2 flips for the past 3 years or so. I have coffin boxes that hold 2 rows of 2x2 flips for easy storage and safe keeping. These boxes have been in trunk in a room on the 2nd floor of our house. Exposure to temp extremes and moisture would have to be low IMHO.

Anyways I was reorganizing the flips and noticed that a coin of mine 1931-D (stored in a hard plastic single penny holder) was starting to show signs of verdigris on the obverse. I was more than shocked to see this occurring on a coin in a hard plastic case. Although i cannot be certain I believe the green patches must have formed only over the last couple years. So what's wrong with my storage? I barely slept last night going through half of my collection. And found a couple other examples where coins look like they are either toning or have what can only be described as sweat patches (i'm particularly concerned about a 1909 vdb that is xf+).

I have also taken steps to remove any coins with verdigris on them from the rolls and now i'm trying to figure what's the next best thing to do with the coins that have verdigris on them. I looked through pages of flips and found NO corrosion. Could airtight plastic coin cases and tubes be the cause of this?

Attached below are examples of what I saw last night:


Please note my 31-D is in much better condition and does not have the craters.



What can be done to a coin that is starting to show signs of verdigris? Most of the coins would be valued less than $5. I've been reading up about cleaning coins by (found athttp://metaldetectingworld.com/cleaning_coin_p6_mechanical.shtml:

1. soak in olive oil for 24hours
2. neutralize by bathing in acetone
3. brush with tooth brush and toothpaste
4. rinse / soak in water
5. dry in oven or other low dry heat source


Any help, comments, advice will be great. I've got about 15 IHC's that i'm going to try various method of cleaning to see which method does the job best without totally destroying the coin in the process.

~JobIII

[Engineer]

Vacuum packing would be your best bet, or a safe heater would also help to protect your good stuff from corrosion.

http://www.goldenroddehumidifiers.com/introduction.htm

[daviscfad]

Number 1 rule never clean a coin. You can soak it in acetone but do not scrub it by any means. Wash it with water and pat dry

[bman]

try some Verdicare. It will remove all light verdigris but would not do much for that IH. Once the verdigris has started to eat away at the metal it's too late.

http://www.wizardcoinsupply.com/products/verdi-care.html

[JobIII]

Back when this post was first started I placed a couple of cents into 2 jars. Filled one with acetone the other with mineral oil. Just about a month has past and the acetone jar looks to be murkier. No change to the mineral oil jar as of yet.

~JobIII

[daviscfad]

a lot of times the acetone will evaporate if left in open air

[JobIII]

Yeah these jars are air tight!!!!

[daviscfad]

Would like to see some photos when your done