Maybe the following book will help you: "Cleaning and Preservation of Coins and Medals" Sanford J. Durst Numismatic Publications Rockville Centre 11 Clinton Av NY 11570 10th printing, 2001 Among lots of others, your iron "notgeld" is mentioned here.
North and South American Silver Coins. Chinese Silver Coins Chopmarks
Coca-Cola has phosphoric acid in it ( and we drink it). This is the same chemical as in Nicalene that I have used on crusty nickels. Cemetarys sell it so you can clean the oxidation off of your loved ones Bronze head pieces. Seems it would work on the iron pieces as well.
Comments
Sorry. I couldn't resist.
Well actually, I could, but I chose not to.
"Cleaning and Preservation of Coins and Medals"
Sanford J. Durst
Numismatic Publications
Rockville Centre
11 Clinton Av
NY 11570
10th printing, 2001
Among lots of others, your iron "notgeld" is mentioned here.
Chinese Silver Coins
Chopmarks
Coca-Cola has phosphoric acid in it ( and we drink it). This is the same chemical as in Nicalene that I have used on crusty nickels. Cemetarys sell it so you can clean the oxidation off of your loved ones Bronze head pieces. Seems it would work on the iron pieces as well.
Krueger