Intaglio printing remains the key security element in banknote printing until today, providing the characteristic feel and tactility recognized by the public. Traditionally, platemaking for this very specific process was done by an electroforming process that involved multiple production steps and manual retouching. We have developed a machine to manufacture these printing plates by direct laser engraving into a metallic substrate. The first machine has recently been put into live banknote production at our premises.
We describe the changeover to this novel technology and give a comparison of our findings on print-quality, plate stability and the workflow with conventional platemaking. Results include
- Mechanical analysis of the new plate material before and after printing,
- Measurements of plate elongation during the printing
- Investigations on print-quality
We conclude with actual data on engraving time and platemaking lead-times and an overview of the design possibilities using this new approach.
The state of the art in manufacturing security documents includes the usage of a multitude of inks and pigments. The chemical and physical stability of these materials is a crucial point for their application in long lasting security products such as banknotes. For our studies regarding the bleaching characteristics of pigments and inks we have developed a highly integrated double beam gonio-spectrometer with in-situ ageing capability. The new spectrometer is equipped with a stabilized solar simulator lamp featuring a dosimeter, which is an advanced alternative to the commonly used blue wool scale. Additionally the sample temperature can be stabilized during ageing tests by a thermostatted sample holder. The instrument is capable of performing reflection measurements using monochromatic and polychromatic excitation and further allows fluorescence, phosphorescence and polarization measurements with high resolution over a wide wavelength range. We will present first results of defined ageing tests on a variety of security pigments and the setup of the newly developed spectrometer.
Traditionally, Intaglio printing is one of the key security elements for banknotes and security documents, providing high-resolution fine-line elements and the characteristic tactility easily recognized by the public. The conventional process of creating Intaglio printing-plates involves multiple production steps from the hand-engraving of the artist and the computer-aided-design of security elements to the final, print-ready metal plate. We present the results of a feasibility study regarding the direct laser engraving of Intaglio printing-plates. Results of our studies on laser optics and choice of material to achieve optimal line quality are presented. In our studies we have found a novel plate material superior to galvanic nickel regarding plate lengthening and have achieved line widths in the 10μm range. The process found, allows reintroducing true three-dimensional elements with line-depth and -profiling control independent of line-width, while decreasing lead-times in the production of security documents. We give a comparison between direct laser engraving and traditional platemaking, comparing aspects such as resolution, plate performance and production time.