B1 Stamp Errors
A stamp error may be a work of a tired printer, a broken printing press, paper waste or an innovative creation at the printing house.
Postage stamp errors occurs by a problem in the printing process.
By a mistake, accident or by purpose..
Inverted overprint is a classic error but there are a lot more kinds of overprint errors
and stamps with perforation errors too
Something can be wrong with he paper making it a stamp paper error. Or a postage stamps printed on the gum side when a paper sheet is put upside down.
It just makes all more interesting for the stamps collector. Sometimes it can be hard to get it right even for a stamp printer.