I have this Belgian 25f from 1922. Can anyone tell me what might have caused the damage (Rev)? It looks like it's been folded and then flattened again, as the metal is quite badly fractured especially through the bottom of the ‘25’, but only on one side.
It's hard to say if this is some kind of PMD (post-mint damage) to the reverse, or if there was a flaw in the planchet that caused the metal to behave this way. If the area in the first photo near 8:00 has missing metal, it could be a lamination error. Maybe some underlying defect caused the other effects too.
The cracks to the surface are right across the whole of the reverse side, with absolutely nothing on the Obverse. Some of the damage looks like the coin has been dented (quite a deep gouge next to the centre hole and the edge by the leaves). But, the cracks appear to be just surface damage, almost as if the surface is starting to flake off. If it were dampness getting into the core of the coin, I would have thought it should produce a bubbling effect rather than this peeling or flaking.
Looks like the same thing - but from 30+ years earlier.
I wonder how long we've been getting this sort of issue? I assume it started when we moved away from solid metal coins (silver/bronze etc.). As this sort of change started, for the most part, after WW1, my coin may be one of the first with this kind if issue.
Each set of production technologies comes with its own set of things that can go wrong.
Defects/impurities/heterogeneities in the coining metal have probably been around as long as coins have been produced. I have 17th century coins with “streaks” that I assume are from such impurities.
I've evn got coins with holes that are not PMD. but were a planchet defect that turned into a hole when the coin was formed.
