Harding 2c #613 - Perf 11

Ummm, it's the same stamp. I think you are missing the lesson here. IF there is a setoff (Ink) on the back of the stamp IT IS a flat plate print, you will not find this on rotary press printings. Your stamp IS Scott 610.

The set-off is due to the flat plate printed stamp sheets being stacked on each other after printing and before gumming. This means that the set-off would occur on the paper under the gum. Some kind of special separation partition shelf was used to separate each stamp sheet after it was gummed so that it was faced down with the gum facing up in order for it to dry.

In the rotary press process, after the stamps are printed, they are dried by the press before they are gummed by the press. Since the paper moves along as a continuous paper web (rather than as individual sheets), there is no chance of there being any stacking before the gum is applied to the paper. Then after gumming, the gum is dried by press driers before it is rolled back up into a printed roll. (If there is any potential chance of any set-off occurring, it would happen after being rolled up and would occur on the gum, but this is very unlikely.)