I recently purchased 2 of the 1971 Isle Of Man coin sets in the little plastic wallet (much like the First British Decimal set):



I got this set mainly for the charming 1p coin

However on taking the card out of the wallet I discovered some green sludge on the obverse:





Both sets have this although this one is worst of the two. I have a dilemma, I want to clean this horrible sludge off but I know it will reduce the set, however the sludge has signifcantly reduced the value of them anyway.

I am going to clean one set regardless (the worst one) but just wondered what the safest & least destructive way of doing it is, Brass-o is a no no & I don't want Barry Scott round my house if I use Cillit Bang (a reference most probably won't understand seeing as most members are from North America), so does anyone know of a safe & cheap way to do it...

... BTW I KNOW that cleaning reduces the value but with the green sludge on there they are pretty worthless anyway, plus I'm not doing it to both sets.

Any help greatly appreciated

Possibly acetone might move it

Thanks for the info, any idea where I can buy it?

As I say I never normally clean coins but considering that this set was possibly mass produced (like the British one) and that the sludge has reduced the value plus I have two sets, I don't feel that I'm committing too much of a sin.

Had it had been a valuable coin in this condition however I would left it as it was

Try a paint suppliers, or at a very big push you could try nail varnish remover, same stuff but roughr as it has additives, not reccomended

Thanks, I want to cause as least damage as possible, unfortunately the packaging smells a bit damp (possibly left in a shed or garage) so they could be perminately damaged under that sludge anyway

But that's the risk with Ebay, the rest of the stuff I bought off of this buy was tip top, perhaps they don't know?

Johnny,
I think the plastic they used in these sets and the "first decimal sets" did not help, I have seen many of these that have developed the dreaded green gunge. As you say the sludge will only get worse over time, and in many cases a light rub with a cotton cloth will visually remove most/all of this, if you do not want to head down the chemical route, but there are no guarantees it will not return.

Is the sludge (verdigris) only on the surface? If it is just wipe it off carefully with a soft cloth as suggested above or alternatively for the copper or Cu-Ni coins soak in olive oil for 10 minutes - most of the sludge lifts straight off and you then pat the coin dry or use cotton buds. The olive oil is fine on most copper based coins and does no damage and at the same time prevents any further damage.
If the oxidation has penetrated the coins surface there is not much you can do.
As stated previously the green or blue surface sludge (also be aware there is also a clear sludge that forms between the plastic and the coin) are the direct result of the chemical reaction between the plastic/polyurothane coin wallets and the metal of the coins. You get a similar effect in the those old plastic coin holder pages people used instead of 2X2's or Eagle mounts etc.

Do not soak them in olive oil, it may cause the cupro-nickel to tarnish as this happened to some of my cu-ni Crowns a month or two ago, and the effect is worse. Just wipe them, unfortunately this verdigris is aptly described by its other name, 'metal sickness' and you cannot 'cure' this! A wipe will improve the appearance and hopefully stop the rot, but I would not use any stronger cleaning methods, especially with the vulnerability of that cute little 1p coin you seem to have a strange thing for..