GRAPHOTYPE ENGRAVING.

Otago Witness, Issue 748, 31 March 1866, Page 16

GRAPHOTYPE ENGRAVING.

(From the Mechanics' Magazine )

At the meeting of the Society of Arts, held on 6th December, Mr H. Fitz-Cook read a paper on a new method of producing, from drawings, blocks for surface printing, without the aid of the engraver, to which the name of " graphotype" has been given, and last week's number of the Society's " Journal" contains some i lustrations printed from blocks produced by the new method. The new process is the invention of Mr De Witt Clinton Hitchcock,

one of the foremost draftsmen and engravers of New York, and was suggested by a little incident which Mr Fitz-Cook thus related: — '• In the summer of 1860, Mr Hitchcock, in the course of making a drawing on box wo-id, found it necessary to alter a portion of his design by erasing it aud re-whiten-ing the exposed surface of the wood. The material used for this purpose was the enamelled surface of an ordinary visitingcard, softened by water and a brush, — a method known to most draftsmen on wood. The card employed happened to be one printed from a copper plate, and after the removal of all the enamelling, as described, the artist discovered that the printed letters were undisturbed, and standing up in bold relief." Hi 9 first attept to carry out the idea which this circumstance instantly suggested to him was made upon a slab of chalk, sawn from an ordinary lump, and one surface made as smooth as possible by scraping. He drew upon the smoothed surface of this, piece of chalk with ink and a quill pen, using ai ink silicate of potash, or " water glass," coloured with indigo, and when the lines of the drawing were dry he brushed away, by means of a tooth-brush (but not using water, as when removing the enamel from a card), all the portions of the chalk surface upon which there were no lines. " The lines of the drawing," we are told, " being literally composed of stone, withstood the assault of the toothbrush, but the intervening particles of exposed chalk succumbed, and vanished in a cloud of snowy dust, leaving the impregnable lines standing in relief, inviting a proof of their strength by printing on paper. This could not be done until the whole ma c s of chalk wa3 changed into stone, by saturating it with the liquid glass, but in half an hour the chalk block was inked and printed in the ordinary way by burnishing." Ultimately, as the result of a great number of experiments, Mr Hitchcock elaborated a process which seems likely to supersede woo>J-engraving, if not for all, at least for many purposes, being much cheaper than wood- engraving, and having moreover the great advantage of infallibly reproducing the artist's every touch, however delicate, with the most perfect accuracy. In its present shape the process is conducted as follows : — An artificial chalk block or pla'e is first produced by grinding the be3t French chalk to fine powder, mixing this powder with water to a thin cream and separating the portion which precipitates firs' 1 , repeating this operation several times, in order to ensure the complete separation of any hard or coarse particle, drying the very finely -divided chalk thus obtained and sifting it, through wire-cloth having 10,000 holes to the square inch, on to the surface of a perfectly smooth plate of zinc, placing a plate of highly-polished steel on the top of the even layer of chalk- flour £thus obtained, and then submitting it to powerful hydraulic pressure. On removing the pressure and lifting off the steel plate, the chalk is found to be firmly attached to the zinc plate, and to present a perfectly smooth upper suriace, which only requires to" be " sized," in order that the iuk to be used in drawing on it may not " spread," to be ready for the artist. The latter proceeds as in the ordinary method of drawing on wood, first making a red chalk tracing on the block of plate, and then with sable hair pencils of various sizes, drawing his design. line for line, exactly as he wishes it to appear when printed. The ink used is a mixture of glue and lamp-black", and dries instantly, so that £one series ol Hues, of whatever thickness, may be immediately crossed by others. The drawing being completed, the portions of the chalk surface intervening between the lines of the drawing are disintegrated and removed, to the depth of an eighth of an inch or so, by means of brushes, some of them of fitch-hair and others of silk velvet, and the chalk block is then hardened by being soaked in a solution of an alkaline silicate. A mould is then taken from the chalk block, and a type-metal cast produced from this mould, by the ordinary process of stereotyping, and it is this type-metal cast, and not the original block, that is used to print from. " The process is so delicate," says Mr Fitz-Cook. "that the impression of the thumb wetted with the graphotype ink, skeleton leaves, feathers, and other objects to which nature- printing ha 3 been applied, can be made to give beautiful impressions in the ordinary type-press, whilst the finest hair-line that the artiafi can make will stand equally well with the bolder work." The type-metal cast may be obtained with ease within three hours after the completion of the drawing on the chalk surface, so that the new process has an immense advantage over wood-engrav-ing, not only as regards cost, but also as regards the time occupied between the completion of a drawing and that of the block, by means of which copies of it may be multiplied by the printing press. While thus cheap and expeditious, the new process reproduces the artist's work with an absolute accuracy unapproachable by the most skilful engraver*