Causes for back doctoring
The ink is collecting around the containment blade in the surrounding area. The containment blade is subject to a designed yield due to dynamic pressure, because the lamella would bend inward. Is the containment blade too stiff or the chamber is subject to too much pressure, the blade prohibits the remaining ink to flow back into the chamber. An ink residue on the outside is the result.
Solutions for back doctoring
1. Check the pressure of the chamber onto the anilox role and adjust pressure according the machine manual.
2. Too stiff doctor blades results problems with flexibility, install thinner, more flexibel blades.
TKM recommends the TKM OptiPrint doctor blades.