A method of printing wherein magnetic particles dispersed in an ink are selectively orientated prior to printing onto a document where the particles are aligned on a carrier while the ink is in a low viscous state and the printing is effected when the ink is in a high viscous state. The method by which...http://www.google.de/patents/US3998160?utm_source=gb-gplus-sharePatent US3998160 - Magnetic ink printing method
