FORVM`s Classical Numismatics Discussion Board

Numismatic and History Discussion Forums => Coin Photography, Conservation and Storage => Topic started by: Philoromaos on April 05, 2009, 02:09:05 pm

Title: Why are my silver's turning green?
Post by: Philoromaos on April 05, 2009, 02:09:05 pm
Hi all! I collect denarii and keep my collection in a coin album but recently I've noticed green patches appearing on some of my coins, especialy on the edges. A short soak in lemon juice seems to remove them but it's also leaving the silver brighter which I don't want. What's causing this and how can I prevent it? Regards
Title: Re: Why are my silver's turning green?
Post by: areich on April 05, 2009, 02:19:58 pm
It's PVC in the plastic. Use PVC free plastic or none at all.
This will also affect other metal though not as quickly, if I remember correctly.
Title: Re: Why are my silver's turning green?
Post by: Johnny on April 06, 2009, 06:03:31 am
this could turn out to be an informative post.  any chance of posting a few pics of the affected coins ?
Title: Re: Why are my silver's turning green?
Post by: Will Hooton on April 06, 2009, 08:01:45 am
It's PVC in the plastic. Use PVC free plastic or none at all.


Andreas is right! The PVC in the plastic is causing the coins to undergo BD. Ensure you store coins in a PVC free sleeves which can found from most coin dealers. I dont know If Joe stocks them.
Title: Re: Why are my silver's turning green?
Post by: bpmurphy on April 06, 2009, 08:23:51 am
I wouldn't use lemon juice to remove the green, it's too strong. Acetone removes the green without affecting the silver or any patina on the coin.

Barry Murphy
Title: Re: Why are my silver's turning green?
Post by: Paleologo on April 07, 2009, 07:37:09 am
The PVC in the plastic is causing the coins to undergo BD.

Although it is common belief that PVC in coin flips can cause bronze disease, I think the "green" in this case is still simple oxidization caused buy chlorine in the plastic (the C in PVC), this is why it can be removed so easily. Try alcohol before acetone (or just demineralized water and a soft brush) for an even softer treatment.

Regards, P.  :)
Title: Re: Why are my silver's turning green?
Post by: Philoromaos on April 07, 2009, 11:58:07 am
I've cleaned them unfortunatly but at the speed they're turning green I can probably get a picture soon, might be a poor picture though, I can't seem to hold the camera still! I've been wanting to get a coin case for a while now but thought getting one to hold over 320 coins would be very expensive, but I searched online and managed to get this beauty for £30! Hopefully no more green coins once this comes!  :) Thanks everyone
Title: Re: Why are my silver's turning green?
Post by: areich on April 07, 2009, 12:07:04 pm
I use a copy stand for my coin photography.
Professional ones are expensive but mine does its job and was only about $40.
Title: Re: Why are my silver's turning green?
Post by: Robert_Brenchley on April 10, 2009, 02:22:55 pm
I get coin flips from Joe, and I've never had a problem with them. Do you live in a damp climate?
Title: Re: Why are my silver's turning green?
Post by: JRoME on April 14, 2009, 02:38:22 pm
Where did you find that case?  And how do I talk my boss into paying me in Euros instead of Dollars?
Title: Re: Why are my silver's turning green?
Post by: Robert_Brenchley on April 14, 2009, 05:54:32 pm
Get him to pay you in aurei, it's a more reliable currency.
Title: Re: Why are my silver's turning green?
Post by: Jay GT4 on April 14, 2009, 06:05:09 pm
That is a nice case!  Details please!
Title: Re: Why are my silver's turning green?
Post by: mauseus on April 20, 2009, 08:43:01 am
Hi,

Just a quick word of warning about "cabinet" abrasion. By constantly lifting the case from a horizontal to a vertical position you can get wear on high points as the coins rub on the liner material, much more so than if coins are kept horizontal for storage and transport.

When I started collecting a long time ago I had an Ellizabeth I shilling that got distinctly polished on the high points when I kept it in such a case.

Regards,

Mauseus