US556975A - Hubert iierkomer and henry thomas cox - Google Patents

Description

Fries.

HUBERT IIERKOMER AND HENRY THOMAS COX, OF BUSHEY, ENGLAND.

MODE OF PREPARiNG ARTISTIC PRINTING-SURFACES.

SPECIFICATION forming part of Letters Patent No. 556,97 5, dated March 24, 1896.

Application filed April 3, 1895. Serial No. 544,259. (No specimens.) Patented in England November 23, 1891 No. 20,346.

To all whom it may concern.-

Be it known that we, HUBERT IIERKOMER, R. A., and HENRY THOMAS COX, of Bushey, in the county of Ilerts, England, have invented certain new and useful Improvements in the Mode of Preparing Artistic Printing-Surfaces, of which the following is a specification, and for which we have obtained Letters Patent of Great Britain, No. 20,3i6, dated November 23, 1891.

The object of the present invention is to prepare, by the aid of the electrotype process, printingsurfaces (in a simple and expeditious manner) which will reproduce, by printing, the artistic touches obtainable only from the hand of the artist.

In carrying out our invention we provide a smooth ground-for example, a copper-plate, such as that used by engravers, but silvered to prevent adherence of the copper deposit on the bare plate-and upon this surface we produce a picture in a medium somewhat resembling greasy ink, the ground representing the lights and the varying thicknesses of the medium the various tones of the picture. From this work, after the treatment to be presently described, we make an electrotype plate from which impressions may be taken after the manner of copper-plate printing.

The mode of producing the picture may somewhat vary without aifecting the ultimate result. One method which we have found eiiicient for certain kinds of artistic work, such as those which do not require much variation in tone, is to coat the ground-plate with the inking medium to a given depth or thickness by a printing-roller or equivalent means, and from this prepared surface to produce the picture by removing parts of the soft coating where the lights and middle tints are required. This result may be eifected by the aid of a piece of rag, a brush, or a piece of pointed wood, according to the character of the artistic touches desired. \Vhen the picture is completed, a margin maybe made by wiping the plate clean for a given distance inward from the edge thereof.

It will be understood that the work of the artist is to remove the coating to a less or greater depth, as maybe necessary to secure the requisite effects of light and shade, (to.

In place of first coating the plate and then removing the inky compound to obtain the lights and middle tints, the reverse method may be employed, and with greater advantage in respect of some classes of subjects where a breadth of light or medium tones prevailthat is to say, the artist will work upon the plate as if he were producing a tone-drawing, laying on the inky medium sparingly or otherwise to produce the varying tints and shadows required to give proper force and perspective to the picture. Thus the lights will be represented, as before, by the uncovered surface of the plate, the distances in the picture by a sparse application of the medium employed, and the deepest tones by the greatest thickness of medium.

The picture produced in either of the abovementioned ways, or it may be by the two methodsin combination, is next to be prepared for the elcctrotype-bath by giving it a metallic surface, on which the copper is to be deposited. when obtained may hold the printers ink in its cavities, it is necessary to produce what is known as a grain in those parts of the plate, which grain must be coarser or finer, according to the depth of tint or tone required for the various parts of the composition. To produce this grain we dust over the picture while still tacky with a granulated or gritty mate rial, which should be of various degrees of fineness. The granulated or gritty material which we have successfully used is a composition of powdered asphaltum and bronze powder in the proportion of two parts of the former and one of the latter. The composition, aftercareful mixing, is placed in a bag of fine muslin and then dusted over the picture until the work of the artist is coi'npletely hidden. The surplus powder is then removed by a soft oamels-hair brush or its equivalent, and that which has come into contact with the picture is retained, the coarser grains bein g held by the thicker coating of the medium, while the films and thinner parts secure only the finer grains. The picture in this state is laid aside for some three days to harden, and it is then ready for the bath. Care must, however, be taken that the surface of the picture is not touched, as it is liable to injury from even a slight amount of pressure.

The electrotype is produced by electrodcpo- In order, however, that the plate sition in the well-known manner, the picture having been by the dusting-over process converted into a properly-metalliz'ed surface.

The inky composition or medium which we employ for producing the picture consists of a vegetable oilsay boiled linseed-oilmixed with German black or lampblack, with the addition of animal fat, which serves to retard the drying of the oil, the proportions being about equal parts, by weight, of oil, of German black or lampblack, and animal fat say lard-oil.

The proportion of the animal fat will vary according to the nature of the picture in hand, it being essential that the thinner parts of the applied medium shall not harden during the progress of the picture.

The retention of the tackiness of the picture is especially necessary when a work of some elaboration is in hand, and some two, three or more days are required to complete it, the premature hardening of the medium preventing the proper atttachment of the granulated mixture and thus rendering much of the artists labor abortive. The electrotype of this plate will be an intaglio representing the reverse of the artists work, and

' the impressions from the plate will therefore It may be understood that in the composition with which the picture is dusted to produce the grain and prepare it for the electrotype-bath, the powered asphaltum being inert to the action of the electrotype-bath only produces the grain and the bronze powder metallizes the surface to prepare it for the reception of the electrodeposit.

What we claim is- 1. The within-described method of producing artistic printing-surfaces in intaglio with a grain, consisting in first forming on a ground or base a picture having a greasy or tacky surface, next dusting over the surface of the picture while in a tacky state a granular substance possessing electrical conductivity and of different degrees of fineness, then removing the excess of the granular substance and finally subjecting the thus-coated picture to the electrotype-bath, as herein described.

2. The improvement in the method of producing printing-surfaces in intaglio with a grain, consisting in first forming on a ground orbase a picture in a greasy or tacky medium, next dusting over the surface of the picture a granular composition consisting of a pow der of different degrees of fineness inert to the electrotype-bath and a metallic powder, then removing the excess of the granular composition, and finally subjecting the thuscoated picture to the electrotype-bath, as herein described.

London, March 14, 1895.

IIUBERT I'IERKOMER. HENRY THOMAS COX.

iVitnesses II. K. WHITE, W. M. HARRIS.