The Model of Intaglio Ink Relief Forming

Abstract

The object of the study was to ascertain the mechanism of intaglio relief forming. The technological features of intaglio printing cause ink relief forming which in accordance with the proposed model consists of a ink layer, under ink relief, and areas of vertical and horizontal ink penetration into substrate. Ink relief forming is a result of the combined action of the high pressure in the printed nip (1,000 kN/m) which is applied slightly differently to different areas of the paper, and increased up to 80–82 °C the temperature of ink on the plate cylinder. The model is experimentally corroborated by microscopic examination of intaglio printed paper cuts with zoom in x100–1000. It was defined the shape of the intaglio ink relief parts, their position on the surface and in the volume of the banknote substrate, and the dependence of their parameters on technological factors. Height of the under ink relief is 10–20 μm (for tested size of engraved recesses) or 40–60 % of the total height of the intaglio ink relief. The ink penetration depth into substrate is 8.0–24.3 μm, lateral ink penetration is 8.0–18.3 μm. Increasing the pressure of the intaglio printing nip increases the depth and lateral ink penetration into banknote substrate. Lateral ink penetration into the paper increases with increasing of paper sizing and decreasing of ink viscosity.