V. Sezonov, K. Dikevych
This article analyzes the component composition of inks, paints and dyes, and also gives a general description of one or another type of ink or dye and a classification of some of them. The historical aspect of the manufacture of inks and their components is highlighted. Writing ink was first made in ancient Egypt and China around 2500 BC. The features of paints depending on the type of printing (high, gravure, flat offset, screen) are studied and examples of their application are given. Flat offset inks used in newspapers are usually simple in composition. As for letterpress, although this type is gradually being replaced by other printing processes, it is still used in the production of money, most paper-based forms in printing serial numbers, etc. Gravure inks are similar to flexographic inks, except that ketones and aromatic hydrocarbons can be used as solvents, allowing much greater freedom in the choice of binders. This type of ink for inkjet printing, such as solvent ink, is considered in detail. Solvent ink is a complex physical and chemical system for inkjet printing, consisting of pigment, polymer, film former, solvent and special additives. The structural composition of solvents is characterized, which, getting on paper, undergoes a number of changes over a fixed period of time, as a result of which the dye dries on paper. Ethanol, benzyl alcohol and many other solvents can also be used as carriers. The choice of solvent or solvents often depends on the properties of the writing instrument. The so-called «invisible» ink (UV ink, thermosetting ink, etc.) was studied separately as a kind of protective element. This type of ink is mainly used in steganography, anti-counterfeiting and currency security features, packaging authenticity indicators, brand protection, and secret messages. Conclusions are drawn, emphasizing that understanding the principle of operation of one or another element of protection allows forensic experts of forensic technical examination of documents to effectively identify forgery.
Key words: document protection, component composition, printing inks, solvent inks, solvents, dyes, technical examination of documents.