Bank-notes, MANUFACTURE OF. The chief thing to attend to in the manufacture of bank-notes is the rendering of their forgery impossible, or at least easy of detection. This is sought to be effected by peculiarity of paper, design, and printing. Bank of England notes are printed in one of the blackest and most indelible of inks on paper expressly made for the purpose by one firm only. It is a hand-made paper, remarkable for its strength, lightness, and difficulty of imitation. Its peculiar water-mark constitutes one of the chief safeguards of the notes against forgery. No Bank of England notes are issued twice, so that this mark is rarely indistinct, and the paper does not lose its peculiar crispness. Some years ago a self-registering machine was invented for impressing on each note a distinctive mark known only to the bank authorities. Owing to some of the notes of the Scotch banks printed simply in black ink having been successfully forged by photography, those issued have since 1858 been printed in coloured inks, at least two colours being used for each note. Still further to lessen the risk of forgery, a new note was in 1885 issued by the Bank of Scotland, printed in brown, yellow, and blue. The paper is similar to that used for Bank of England notes, with an elaborate and easily recognised water-mark. In 1887 the Commercial Bank of Scotland also issued a note, printed in yellow and blue on the face, and with a dark-brown device on the back. In 1893 the National Bank of Scotland issued a note with elaborate portraits and landscapes. Foreign bank-notes are also printed in coloured inks. The actual cost of one-pound notes is as nearly as may be one penny each, and of larger notes only a fraction more.
Between 1837 and 1855 the plan of Perkins and Heath for reproducing an engraved steel plate by the use of the mill and die continued in use in the Bank of England. The pattern is engraved on a soft steel plate, which is then hardened, to transfer the pattern by pressure to a soft steel roller, on which, of course, the pattern is produced in relief; the roller or mill is then hardened, to reproduce the pattern in the plate from which the printing is to be done; and thus almost any number of plates for all common purposes can easily be produced.
In 1855 electrotype-printing was introduced by
Mr Smeé, with the assistance of the mechanical officials (see ELECTRO-METALLURGY); and since then, the notes of the Bank of England have been all produced by surface-printing from the electrotype.
The number of notes produced and issued by this bank sometimes amounts to 300,000 per week. There are seventy or eighty kinds of Bank of England notes, differing in their denominations or values, but similar in the mode of printing. Zincography and lithography are employed by some banks for the printing of their notes; and also acicrage, a mode of hardening copper electrotypes with a thin surface of steel.
In the United States, the bank-notes at present in circulation are manufactured by the government bureau of engraving and printing, the paper being made by a private concern under a patented process, the chief ingredients being a mixture of linen and cotton fibre, into which are introduced threads of silk, so arranged as to be perceptible after the notes are printed. This style of paper is furnished only to the government. Superior skill is exercised in engraving the plates, nearly all parts of them being executed by the geometrical lathe and the ruling-engine, the work of which it is impossible to imitate successfully by hand. The printing of the notes is done in coloured inks of the best quality, sometimes as many as four shades being used. The great expense of the machines used in the engraving, and the superior quality of the work generally, renders successful counterfeiting almost impossible. The notes when badly worn are returned to the United States Treasury, other notes being issued in their stead. See GREENBACKS; and for the question of a paper-currency, see CURRENCY.