the metal panel in the tableau is originally painted with wrinkle. Only on the visible side, the back is just plain black.
Here pictures of 2 panels original from Jaeger.
On the new made, or repainted, panels the wrinkle looks more shiny and real black, where the originals are a little bit brownish and have a finer structure.
Another possibility is powder coating, in that case both sides and the inside of the holes are painted.
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