Ink Bleed On The Back Of The Stamp

Hello..

I am interested to learn about ink bleed on the back of the stamp, which is a mark from stamp production process. Would like to know what caused these ink bleed. Why the ink bleed formed a dots instead of line and why the bleed occurred mainly on the edge.

Back


Front

It is called 'setoff'* and comes from the stacking of not yet fully dried sheets of stamps upon one another. It is a defining characteristic of the flat plate printing process. Sometimes the setoff is so pronounced that you can see an entire reversed image of the stamp design.
Don

*Some folks also use the term 'offset' but in my opinion this is needlessly confusing since their is also a printing process with the same name.