What is "doctor blade"

n. (context printing English) A metal blade used in printing for scrape off excess ink or toner from the printing roll.

In rotogravure printing the doctor blade (from ductor blade) removes the excess ink from the smooth non-engraved portions of the image carrier and the land areas of the cell walls. Doctor blades are also used in other printing and coating processes, such as flexo and pad printing for the same function. It is believed that the name derives from the blades used in flatbed letterpress equipment for blades used to wipe ductor rolls, and "ductor" became doctor.