Modern litho printing involves creating an image in a polymer coating which is then applied to an aluminium plate. The surface of the plate is roughened and manipulated chemically so that some regions are hydrophilic and act to accept water, and repel ink, while others are hydrophobic and act to repel water and accept ink. As a consequence, printing can be done directly from the aluminium plate, resulting in a reversion of the image, or the image can be transferred onto a sheet of rubber.
The main process of litho printing is the production of hydrophobic and hydrophilic regions on the stone or aluminium plate. The terms hydrophobic and hydrophilic are chemical terms, literally meaning ‘water loving’ and ‘water hating’ respectively. Unlike processes of etching, or engraving, the plate does not act as a ‘stamp’ with raised sections. Instead, the entire plate is at the same level, with the ink adhering or not based on chemical reactions. To find out more about our litho printing services visit us at www.pepper.co.uk
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