burr

burr.
A term applied in printmaking to the tiny upturned edge of the incision made in the metal plate by the cutting tool (in line engraving or drypoint) and also to the overall sandpaper-like roughening of the plate created by the rocker in mezzotint. In line engraving, where maximum sharpness is required, the burr is removed, but in drypoint it is allowed to remain because the soft, velvety quality it gives to the printed line is considered one of the attractions of the medium. In mezzotint it is the foundation of the process. With both drypoints and mezzotints, only a limited number of impressions can be taken before the burr wears down.