I think 50 years and farther back all those old tin coffee cans had a "key " the unwound the seal , just as sardine cans used to have ...More than fifty years ago, Chock Full O'Nuts coffee came in cylindrical cans. You opened them by unwinding a metal strip with the key that was soldered to the bottom of the can.
In New York, Chock Full O'Nuts had lunch counters.
At SOME point Ma stopped using "the percolator" and switched to instant ... but that, and Maxwell House was usually in it.
AA