Optical Document Security, Third Edition
Containing over 150 illustrations, including actual security documents, this book delivers a comprehensive and cohesive treatment of all aspects of optical document security.
TABLE OF CONTENTS Optical Document Security, Third Edition
Chapter 3: Substrate-Based Security
3.1 Introduction
Paper substrates have been with us from days of old. It is only very recently that plastic substrates made their appearance in the field of document security, witness our plastic debit cards, credit cards, and identification cards, soon followed by the issue of polymer bank notes in Australia, New Zealand, and other countries. This chapter discusses security features that can be incorporated in the substrates of paper and plastic valuable documents.
3.2 Paper Substrates
Security paper is manufactured on behalf of valuable documents for one particular application and for one particular contractor only; hence, it is not commercially available for the general public. Generally, security paper is provided with several security features that are added during its manufacture. Examples are chemical reactants, watermarks, fibers, planchets, and threads. In later stages of the valuable document production, various types of mechanical perforation and laser perforation may be put to use to further enhance the security level.
3.2.1 Composition
Paper consists of a mixture of cellulose fibers and various chemical additives. The fibers are derived of wood, cotton, or pure cellulose in the case of superior papers. A sheet of paper consisting only of cellulose fibers is water absorbent, so that water-based inks will penetrate the paper and spread in it. In order to reduce this wetting, papers are impregnated with various substances, a process called sizing. Fillers are added to the paper pulp in order to whiten the paper and increase its opaqueness. Because the filler also occupies the...
Copyright Rudolf L. van Renesse 2005 under license agreement with Books24x7
