How can a doctor blade flaw be constant?
Posted: Tue Jul 19, 2011 7:00 pm
Dear All,
Can somebody explain how a doctor blade flaw can be constant?
By definition, the doctor blade is moving all the time during the printing, and the paper on the web is also in constant motion, and the chances of an exact repeat must be virtually nil.
Is it then possible for a doctor blade to damage the surface of the cylinder, and thus the flaw is doctor-blade-caused? Would such a scratch normally be erased with the next cleaning and re-chroming?
If so, it casts all those doctor blade lines in a new light, since instead of being dismissed as once-off accidentals, they might be constant flaws.
(I'm working with 1936-1937 photogravure material, in case that is relevant).
Sorry if this reads like a novice question... I guess it is!
Cheers, and thanks for any insight.
Robin R
Can somebody explain how a doctor blade flaw can be constant?
By definition, the doctor blade is moving all the time during the printing, and the paper on the web is also in constant motion, and the chances of an exact repeat must be virtually nil.
Is it then possible for a doctor blade to damage the surface of the cylinder, and thus the flaw is doctor-blade-caused? Would such a scratch normally be erased with the next cleaning and re-chroming?
If so, it casts all those doctor blade lines in a new light, since instead of being dismissed as once-off accidentals, they might be constant flaws.
(I'm working with 1936-1937 photogravure material, in case that is relevant).
Sorry if this reads like a novice question... I guess it is!
Cheers, and thanks for any insight.
Robin R