Printing Innovation Asia Issue 10 2020
50
RGB Printing – And It Does Work! The Swiss artist and printer Lorenz Boegli developed a method to print RGB. With this revolutionary technology completely new opportunities open up for the printing industry. We all know that RGB cannot be printed. This colour space is designed for screens and other self-lit systems. For printing purposes, there’s CMYK and this is how the world works. But is this still true? What is when an artist and printer, named Lorenz Boegli, developed a way to print RGB? Because that is what he actually did! And the result is a fantastic and innovative new printing technology. RGB vs. CMYK Until now, it has not been possible to bring the multi-faceted and luminous RGB colour space onto paper or other substrates in a single printing process. As an additive colour system, RGB is reserved for luminous media such as screens or beamers. RGB are light colours, colour perception is created by mixing light. This is why it is also called an additive colour model. The more colour is used, the brighter the picture becomes. If you use all three basic colours 100%, you get white. CMYK, in contrast, is the subtractive model. It is composed of the three colours cyan, magenta and yellow as well as the key colour black, which are printed on a (usually) white background. The more colour is applied, the darker the result will be. The key colour is
necessary because 100% application of cyan, magenta, and yellow does not produce a true black, but only a dark brown. An Innovative New Printing Method Boegli’s RGB print, however, is printed on black paper and blends into brilliant white. This is possible thanks to reflective pigments in the colours. „In 2013, by using red, green and blue Spectraval pigments from Merck on a black background, I succeeded in creating white by overprinting the three primary colours of the additive colour mixture. This succeeds thanks to reflective pigments in the colours,” Boegli stated. In the meantime, Merck and Boegli have further developed the technology and made it available for common printers. RGB printing with Spectraval™ works on conventional printing equipment, so it can be incorporated into standard screen, gravure, or flexo processes. The four key work processes are: The image file is separated in CMYK and placed in the negative. In this way the colours red, green and blue are obtained.
For the screen production, a fine screen raster is chosen for maximum colour application. For printing, the special colour pigments are mixed in high concentration in conventional screen printing varnishes. During the printing process itself, a low printing speed is important to ensure the ideal alignment of the individual pigments. For the presentation of the new RGB printing technology at drupa 2016 Merck cooperated with STAINER, which produced 3 mm thick 2750 x 1875 mm aluminium composite panels for an RGB exhibition wall. For this purpose, the aluminium panels were first pre-printed in black using screen printing and then printed with red, green, blue and silver-white using the RGB printing technique with the provided motif. An increasing number of areas are now turning their attention to RGB technology as the impact of additive printing literally catches the eye of companies and customers.
