A continuing trend in the printing industry is the increased use of specialty inks, not the least of which are the metallics. To achieve the desired specular reflection characteristics, metal flake pigments are used in the ink formulation. In order to provide a reasonable match to the expected printed product, a direct digital halftone color proofing was developed utilizing the same metal flake pigments as are used in typical lithographic inks. The use of non-volatile pigments necessitates the use of bulk transfer donor architecture. A two-layer film structure was developed wherein a metal flake pigment containing layer overlies an IR radiation sensitive propellant layer. Gasification of the propellant layer upon exposure by an 830 nm laser diode array provides the motive force to transfer the pigment layer from the donor to a receiver. Donor structure options, imaging mechanism sensitivities, and salient material properties are discussed.
David A. Niemeyer, "Metallic Donor for Direct Digital Halftone Proofing" in Proc. IS&T Int'l Conf. on Digital Printing Technologies (NIP18), 2002, pp 718 - 722, https://doi.org/10.2352/ISSN.2169-4451.2002.18.1.art00072_2