The Examination of Printed Documents
Michael John Allen · 2015
This chapter deals with professional printing machines such as letterpress and offset lithographic printing presses. Whatever printing process is used to produce a document, a number of general issues will often apply. The chapter deals with these issues by discussing the properties of the inks that are used, how different colours are produced and how to reproduce images without applying such large amounts of ink to the paper that it will soak in and spoil the product. The chapter explains some printing techniques that are typically encountered in forensic casework. Relief printing processes use a print plate in which the printing surface is above the background, non-printing surface. The devices using relief printing processes include letterpress and stamping devices. In planographic printing, the printing and non-printing areas are in the same plane.