Color and permanence issues in 3D ink-jet printing

3D ink-jet printing is a powder-based rapid prototyping (RP) technique. It is based on the conventional ink-jet printing method. The digital 3D model can be obtained by e.g. 3D scanning or by designing in 3D modeling software. The model is virtually sliced in layers, which are being printed by consecutive layers (cross-cuts) of basic materials, powder and binders. As the 3D printing by ZCorporation, described here, is capable of printing in “full” color, it uses both clear and colored binders. Their current systems use either a combination of CMY or CMYK colored binders and the color is achieved similarly as in conventional color ink-jet printing. In this work, the basis of color reproduction and color measurements methodology, as well as the color permanence or color stability, are described and discussed. The issues which are explained include design of 3D color test charts (generic and custom developed) as color visualization aids, color appearance and color variations in 3D prints, color measurements of 3D prints and color permanence of 3D prints. The work further explains the current possibilities of color 3D ink-jet printing and defines the importance of color monitoring and control, as well as the color permanence issues, in 3D printing.