"Slag" is a term for impurities found in prepared metal that didn't get filtered out. On occasion it can be found on coining metals, especially silver coins. Like other impurities, slag can prevent proper bonding leading to laminations. Observe the struck-in slag after the date on this war nickel and the lamination it caused. In a couple weeks I will show a neat slag error on a Franklin half dollar. Enjoy!
I have a question. I see something going on under the 5 in the date....(the 4 looks odd too). Is that because of the slag? or something else