ABSTRACT
Your question relates to a discussion concerning the class of electrostatic marking physics in which an image dependent electrostatic force is obtained through a variation in the particle charge under constant electric field conditions. One method for obtaining an image dependent variation in particle charge is to use powder that is photoconducting. To my knowledge, there are no commercial sources of such materials since there are no products based on this imaging physics. However, about 25 years ago the Japanese ship building industry used this imaging physics to mark large steel plates for cutting. The process was to coat the plates with a powder (large size) containing zinc oxide, charge the powder in the dark, expose the powder to an image from a projector, and then remove the light exposed (discharged) powder with an air jet. Although this marking method was suitable for large scale marking, it is not practical for document printing that requires a particle size of approximately 1 0 micrometers.
