Is this only on painted interior drums? I have to wonder if it's because the old dye based ink they used back then can't absorb into the wood when it's painted? It can only dry by oxidation which will make it easy to rub off. As the ink will never really dry and cure as designed. It just "chalks" as I call it. Add 40-50+ years of age and they are very fragile I'd think. I think Creighton is a rubber stamp guy hopefully he can chime in. I know it's only original "once" but has anyone tried to restamp a date that's been wiped off?
This occurred to me last night. I remembered seeing an old date stamper lying around and figured I could re-stamp it. I just have to remember where I saw the stamp.
You are right about the ink. There is every chance I would have smudged with my fingers whilst cleaning the outside. It disappeared with the slightest wipe.
Caddywumpus - It wasn't dirty and I wish I had left it alone now. It just had a bit of dust etc from 50 years of existence.
BTW, here's the drum in question. Looks really nice after the clean up.