Could also have been all the exposure to aluminum etc during the war. We have his POW cup, where they would give him his spoonful of watery soup. It was an old tin can, and he had attached barbed wire to it as a handle. At some point he gave away the spoon, which was worn flat from trying to get every last drop. I have often wondered being as old as it is and from German origin if it's not soldered with lead, as the joints are very visible unlike modern tins. Had started life as one of their fake milk tins or "klim cans" as the POW slang went