Knight's Mechanical Encyclopedia, S., Steel-plate En-grav′ing.

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19th-Century American

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Steel-plate En-grav′ing.

This art does not necessarily differ essentially from copperplate engraving; the change, however, in the material operated upon has led to various modifications in the process which could not have occurred with copper; to wit, the inherent capacity of the metal for hardening and softening.

Like copperplate, steel may be engraved by various modes, in line, stipple, mezzotint, aquatint. (See engraving, page 804, where a list occurs of the various modes, each described in its alphabetical place.) The prime art of engraving, and the one to which artists refer when speaking of engraving as an art, is known technically as line-engraving, in which the work consists of lines of various forms, the characters of skin, hair, fabric, wood, metal, ground, foliage, water in motion or calm, cloud, or sky, are given by various kinds of lines; the force and prominence being due to the depth, width, and nearness of the lines, enabling them to hold a greater body of ink in the places where depth of color is required, according to the effects required in the picture.

The origin of the art of engraving is very ancient, and is referred to in engraving, page 804; and copperplate Engrav-ing, page 618; that of steel-plate engraving can hardly be said to have existed previous to Jacob Perkins, of Massachusetts, the inventor of the transfer-process. This is described under bank-note engraving, page 228, and the transfer-press is shown and described under that caption. (See also transfer-press.) It was invented by Perkins, and brought into operation by him in England about 1837, the firm name of “Perkins, Fairbairn, and Heath” soon becoming famous in this branch of the art. The system, however, has never flourished to any notable extent in England, the Bank of England authorities. it was thought, taking a dislike to it as a foreign innovation, and preferring a system which does not produce artistic results, but those of a certain clear and clean precision and unvarying character. They have also, as mentioned in page 229, adopted surface-printing, as distinguished from the ordinary copperplate printing (see pages 618, 619). The Bank of Ireland adopted the Perkins method.

Nowhere has the transfer system been carried to so great an extent or perfection as in the United States, and especially in the Bureau of Engraving and Printing, United States Treasury Department. This bureau was organized by S. M. Clark, under the act of June 11, 1862, and has been in charge of G. B. McCartee since August, 1868. The engraving division is superintended by G. W. Casilear.

To these officers the writer is indebted for much of the folowing information, and for specimen of work on Plate LXIV. to illustrate the subject.

The process in the U. S. Treasury is as follows:—

A piece of decarbonized steel, one eighth of an inch in thickness, and somewhat larger than a bank-note, is softened by artificial means, to make it ready for the engraver, who is necessarily an artist of great skill and experience. The engraving of a single die often occupies many months, but, of course, this is a variable element, depending upon the difficulty and size of the work. The principal engraved work of the bureau consists of vignette portraits and the ornamental work upon bank-notes, with which all are familiar. The denomination counters, consisting of a variety of oval and circular forms interlacing each other in a series of lines and elongated dots, thus forming curious and complex figures, are executed by a geometrical lathe, a complicated and ingenious mechanism having almost kaleidoscopic powers in the production of geometric figures and designs. This is described under rose-engine, pages 1983, 1984. See also geometric lathe, page 963.) When the engraver's work is completed, being in intaglio, the steel block, now called [2369] a bed-piece or die, is subjected to the hardening process. It is inclosed in an iron box filled with charcoal of bone or ivory, and heated to a white heat, after which it is withdrawn and plunged into a bath of oil, a process familiar in the arts. Having thus been hardened, it is placed upon the bed of a transfer-press (which see), a decarbonized cylinder roll adjusted over it, and then submitted to pressure, the roll being moved backward and forward until it has received an impression of the original plate in relievo. (See roller-die, Fig. 4403.) The roll itself is then hardened, and is capable, by means of the transfer-press, of repeating the original engraving upon the softened steel-plate from which the notes are to be eventually printed.

As the different portions of a note are upon separate rollers, great care is required in assembling the various impressions, each being in turn adjusted above the portion of the plate where its design is to occur. This is originally a matter of extreme delicacy, requiring taste and care of no ordinary degree. but as necessity occurs for making other exact copies of the same engraving, a register is kept of the exact position of the roller relatively to the surface of the plate for subsequent guidance. The notes are printed in sheets of four, so that the necessity for this accuracy occurs even in the first plate, as it afterward recurs in the preparation of succeeding plates of the same denomination.

Plate LXIV illustrates several features in bank note engraving: the vignettes executed in line-work by etching, graver, and ruling-machine originally, although the plate from which the impression is taken is the result of the transfer process described. At the bottom is a specimen of the work of the roseengine, and is known technically as a counter, forming a shield, label, or escutcheon, according to shape, on which a number, as “500” or “1,000,” is worked, as familiar, especially in smaller denominations, to all of us.

The securities of the government are printed on distinctive paper, made by J. M. Wilcox, of Glen Mills, Delaware County, Pennsylvania. The essential feature of this paper is a localized fiber imbedded in the body of the paper at the time of its manufacture on the Fourdrinier machine (1, Plate XXXVII.). By the localization of different fibers upon particular sections of the printed notes of various denominations, the raising of notes to a higher denomination is prevented. This mode of making paper belongs exclusively to the government, and as it necessitates large and expensive machinery, it furnishes an additional safeguard.

The mode of trimming and separating the currency is the invention of Mr. Larmon, the engineer of the bureau.

The most important feature introduced into steel-plate engraving since the invention of the transfer-process by Perkins is an adaptation of the process by G. W. Casilear, the superintendent of engraving, to the reproduction of engraved letters and script by rolling in the separate letters of a word from a roller-die which has all the letters of the alphabet on its periphery. It was formerly the practice to engrave each line of lettering, which was then taken up on a roller and transferred to the plate, as described with artistic designs; but, by Mr. Casilear's method, a complete alphabet of any required style, plain, ornamental, or script, is engraved on a plate and taken up on a roller, which is then used, one letter at a time, to produce any word or line required upon the plate which is to furnish the impressions. A force of two men is now sufficient to do the work formerly done by twelve, and in a more accurately uniform manner.

Other improvements have originated in the bureau, among which may be cited devices to prevent the alteration of numbers; an automatic register adjusted to every press and to the paper machinery, to keep an accurate account of every sheet worked; a process for water-proofing notes and fractional currency; the adaptation of power to the numbering-machine; an improved medallion-machine which rules with greater precision and celerity than by previous methods; a peculiar process by which the seal is attached by surface-printing (which see).

It may be added that the note itself is the joint product of peculiar paper and of impressed designs of the ordinary plateprinting process and of the surface process; the rose-engine work is capable of being worked either way; and by an adaptation of Mr. Casilear the medallion work can be made of a compound series of crossing lines, giving a network appearance and a texture which produces very happy effects. See surface-printing.

The conduct of the bureau, in a commercial point of view, and the security of its plates and impressions, might well form the subject of some paragraphs, but this work deals rather with the mechanical and artistic branches of the subject than with the financial and policing features. In regard to the first it may be stated, as an instance in relation to one series of government issues, that the greenback series, so called, of 1869-75, embracing nine denominations, which have never been surpassed in excellence and artistic finish, and which have been suryears in circulation, two alone of the notes have been attempted to be counterfeited, and these but rude in comparison. In regard to the latter feature, that of security in the business method, it may be stated that for the entire term of Mr. Mc-Cartee's incumbency, the loss to the government, whether from theft, delinquency, or otherwise, has not equalled in percentage the loss resulting from the abrasion of gold coin of an equal amount in a single count.

1877.

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Knight's Mechanical Encyclopedia
Knight, Ed.

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Steel-plate En-grav′ing.

Knight's Mechanical Encyclopedia Knight, Ed.

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Table of Contents:

Steel-plate En-grav′ing.

Knight's Mechanical Encyclopedia
Knight, Ed.