5 - 2010 Journal of Forensic Document Examination - 5 PRINTING PROCESS IDENTIFICATION: A MICROSCOPICAL ATLAS Joseph G. Barabe 1 There are few areas in the work of forensic document examiners (FDEs) that rely so heavily upon the use of the microscope as does printing process identification, as many of the identifying characteristics are only observable at higher magnifications than those available with the unaided eye or the hand magnifier. A microscopical atlas consists of photomicrographs (photographs made with microscopes) accompanied by descriptions highlighting the most distinguishing features. This atlas attempts to include most of the printing processes an FDE is likely to encounter in case work, as well as many historical and fine arts printing processes which constitute the foundation upon which modern printing processes stand. While every attempt has been made to include all important processes, it is, as are all atlases, inevitably incomplete. The FDE is encouraged to methodically collect and study printing process specimens, especially those relevant to office and personal use. A list of references is included for further study. Reference: Joseph G. Barabe (2010). Printing Process Identification: A Microscopical Atlas. J. Forensic Document Examination, Vol 20, Pp. 5-37. Keywords: Printing Process Identification, Microscopy, Relief, Intaglio, Planographic. 1 Joseph G. Barabe, B.A., Senior Research Microscopist and Director of Scientific Imaging McCrone Associates, Inc., Westmont, Il. USA. E-mail: jbarabe@mcrone.com 1. Introduction Before the birth of the computer and its proliferation in the 1980s, the forensic document examiner (FDE) rarely had to deal with printed matter, and, if so, it was mostly typewriting. The question was invariably, “What machine produced the document, and when?” If need arose as to other forms of printing, the number of possible choices was not large. Nor did the commercial printing world impinge into that of the office and home. Not so today. The distinctions between home, office and commercial printing have largely evaporated, and legal documents are now generated using many different printing processes. The FDE is often called upon to render opinions regarding some of these processes: Is the document an original, or a reproduction? Were all the documents in a series created using the same printing method or machine? Was the printing method available at the purported date of creation? Has the original document, or part of it, been altered in some way? In this field, the examiner is truly a professional microscopist. Microscopists generally rely upon two bodies of knowledge in order to make an identification: first, general background knowledge in the subject material, usually gained through formal study (classes, workshops focused reading or mentorship); and second, a knowledge of the individual characteristics specific to the object or process, gained from a detailed study of original samples and aided by atlases and other reference material. The first helps to define the universe of possible identifications, and the second the criteria by which to narrow the universe of possibilities, ideally, to just one element in the