Many Belgian coins made of zinc develop a patina over time, and often this patina makes the details of the coins (both languages) impossible to read. The patina is bothersome in my opinion. Is there a method of removing the obfuscation without damaging the coin itself?
Zinc coinage was another WW2 German atrocity in the occupied countries. I don't think you can do much with them. Perhaps a soak in mineral oil and some work with a toothbrush?
Zinc is so soft that I'd think a toothbrush would just finish them off. Zinc is a really reactive metal. Unlike silver or copper, it reacts with both acids and bases. There may be something that would complex with the oxide layer and dissolve it without attacking the metal, but I'm not enough of a chemist to figure it out. (I found a metal-detecting site that recommends soaking them in dilute sulfuric acid, then rinsing them with sodium hydroxide solution. I wonder if the person who posted that advice has ever actually tried it. Each soak would be dissolving the coin's surface.)
Yeah, they're a mess. Zinc, while it has its industrial uses, is a trashy metal for coinage (hence my prior jab at the Nazis for using it everywhere they went). A detecting buddy of mine dug a Nazi 5-reichspfennig zinc coin once, as I recall (it must have come to Georgia as some GI's WW2 souvenir). I worked on it with a fine brass wire brush, simply to make the details more visible. Naturally this is not how you should treat a coin under normal circumsances, but since it was already shot, the main goal was just to make the date and details visible. As I recall, the brass wire brushing did an acceptable job of that. Then I painted it with clear fingernail polish to seal it.
An old time collector used a soak in white vinegar and a nylon brush and then a rinse in water followed by a dip in acetone to remove any microscopic water remnants. Time of vinegar ( acetic acid) soak determined by experience, so watch it. Jim
It's hard to find any of the WW II zinc coins in Unc and Belgium is the only country I've even found Gem zinc.
Interesting! Maybe it's because the issue is oxidation/corrosion instead of just wear. Even if you keep the coin away from physical wear, it's going to be exposed to air and water vapor and tend to corrode.
I have the same problem with my Belgian, Swiss, and Norwegian wartime coinage. Should have followed the lead of the Swedes and used iron instead!
Sweden was a major iron producer, and they weren't a belligerent. The occupied countries probably wouldn't have had the choice to use iron!
