Ernst, I once heard of a conversion of a 6 color Design Jet 90 (18 inch) being converted from dye to pigment. The discussion went like this: If the black is pigment, which it was, then the technology should let you re-fill empty color carts with HP color pigment. The risks are small with this machine because of the two colors per printhead. And the printheads are cheap, like $50. Worth a try? Well the contributor thought so and seemed to be successful. For how long? I don't know, he left the forum soon after.