US634259A - Printer's overlay and process of making same. - Google Patents

Description

No. 634,259. k Patented oct. 9, |999. E. BIERSTADT & T. B. DE VINNE. PRINTERS UVERLAY AND PBUCESS 0F MAKING SAME.

(Application filed Dec` 31, 1897. Renewed May 24, 1899.) (No Model.)

UNITED STATE-s PATENT OFFICE.

EDWARD BIERSTADT AND THEODORE B. DE VINNE, OF NEV YORK, N. Y.

PRINTERS OVERLAY ANDPRO'CESS OF MAKING SAME.

SPECIFICATION lforming part of Letters Patent No. 634,259, dated October 3, 1899.

Application filed December 31, 1897. Renewed May 24, 1899. Serial No. 718,108. (No model.)

To all whom it may concern.- Y l Be it known that we, EDWARD BInRsTAD and THEoDoRE B. DE VINNE, citizens of the United States,residing in the city, county, and State of New York,.have invented certain new anduseful Improvements in Printf ers Overlays and Process of Making the Same, of which the following is a specification.

This invention relates to a new mode or process of making printers overlays and to the novel overlays thus produced. In printing pictures for'books, magazines, newspapers, &c.-such as woodcuts,photo.en gravings, half-tones, and such pictures as are usually printed on typographical presses-it has been found necessary for good results to emphasize various portions of each picture by a system of pads known as overlays7 These are usually made by noting the weak points in each print or picture and pasting one or more t-hicknesses of paper over these parts until the thickness becomes suflicient to cause sufficient extra pressure on these parts in printing to take up the amount of ink. re-v quired to produce the desired effect, the necessary gradations of tone being attained by scraping or leveling off the surface. The overlay thus produced is then applied on the tympan-sheet facing the relief-plate. The preparing of these pads or overlays requires much time and skill.

The object of this invention is to lessen the expense and produce an overlay that has all the good qualities that can be expected without requiring extraordinary skill in its preparation. To do thissuccessfully, we resort by preference to photography. The well-known action of light on bichromated gelatin renders it easy to make a photographic picture of homogeneous composition and of varying degrees of thickness which can be laid over-the relief-plate in the proper position, and thus form a perfect substitute for the usual overlay 'made of several thicknesses of paper.

To enable any one familiar with printing to understand the process fully, we will explain the preferred method of manufacture,

We first make an impression of acut,photo engraving, or half-tone on a thin sheet of Celluloid 0r thin translucent paper. This is or may be strengthened, if required, according to taste or judgment. This may be done v using.

by dusting over it in places fine plumbago, Venetian red, or any iine dry pigment, or it may be darkened with india-ink or otherwise water and eighty grains bichromate of potash will give suitable results. Of this we pour enough on a piece of plate-glass placed in a perfectly level position to stand about one-sixteenth inch deep, let it stand in a cool dark place until the gelatin is set, and then set it awayin a dark room until it is perfectly dry. This may be done some days in advance of The plates are now sensitive to light and must be kept in the dark until used.

XVe place the perfected or retouched print above referred to in contact with the gelatinized plate in a pressure-frame and expose it to light in the same manner as the well-known method of silver-printing in photography. After eight or ten minutes it may be examined by turning the frame over and viewing the back of the glass. lf all the details of the picture are visible, it may be removed. It is take a thin sheet of gutta-percha previously attached to the surface of paper or thin cloth, soften it by heat, and press it in contact with the plaster matrix-as, for example, ina common letter-copying press-the pressure being sufficient to cause the soft gutta-percha to adapt itself to all the variations in thickness of the matrix. After the gutta-percha has become cool, the paper being dry, we detach itfrom the matrix,and the operation is ended. The gutta-percha sheet thus formed is found to vary in thickness in proportion, or approximately so, to the variations in depth of tone or shade in the print, the lighter portions of the print appearing as the thinner portions of the sheet andthe darker portions of the print being found as the thicker portions of the sheet, so that the sheet of gutta-pereha has all the requisites of an overlay. If the operation has been conducted with such skill and judgment as any competent person can readily acquire after a little practice, the variations of thickness of the gutta-percha will be exactly such as are required in an overlay to give the best results in printing.

The accompanying drawings indicate approximately the successive stages of the operation just described.

Figure lis a cross-section of a printingplate or eut, a being its printing-face, and l) its mounting to bring it type-high. Fig. 2 is aseetion showing in alinement therewith the paper cto be printed on and the overlay (l be hind the paper, the variations in thickness of the overlay being greatly exaggerated. Fig. 3 is a sectional view of the gelatin plate e after it has been photo-exposed and subscquently swelled, the variations in thickness being similarly exaggerated. Fig. 4 is a section ofthe plaster matrix f, made from the swelled gelatin plate c. Fig. 5 is a cross-seetion showing the gutta-percha sheet pressed into the plaster matrix, so as to conform to the variations of thickness thereof, the guitapereha sheet thus formed being the photooverlay of Fig. 2.

A cast of gelatin, papier-mche, or any other homogeneous plastic material may be made on the same plaster matrix instead ot gutta.- percha with more or less success.

Instead of plaster-of-paris a mixture of wax, spermaceti, and asphaltum or rosin may be used as a mold for the reliefs; but in this ease some other substance than gutta-pereha should be used for the overlay, such as requires no heat or not enough to impair the matrix.

Another method which gives good results is to make a negative by placing the celluloid or transparent print in contact with a photographie dry-plate exposed for a few seconds to a weak light, then develop the negative as usual, fix, and dry, and it is ready for the next operation. For this we prepare in advance a tissue consisting of paper with a thick coat of gelatin containing a little pigment, or even without any. This tissue can be prepared in advance and will keep indefinitely. Vhen required for use, it must be sensitized by immersing it in a three-pcr-cent. solution of bichromate of potash and dried in the dark. Then dry, we place it in contact with the negative and expose to light, and when it has been sufficiently impressed it is placed in water for a minute ortwo. Vhen it stretches out tlat, )lace it face down on a piece of glass, squeeze out all water until it shows a perfect Contact free from air-bells, lay it between sheets of paper under pressure for fifteen minutes or more, and then place it in warln water until the gelatin softens sufliciently to permit spontaneously.

the removal of the paper, so that it will leave the gelatin tissue on the glass. Now gradually increase the temperature of the water and rinse the surface of the glass until all the surplus of the gelatin not affected by light is dissolved and washed oft. Then dry the plate lVhen dry, place over the entire surface a sheet of smooth paper, avoiding air-bubbles, and allow this to dry, then detach it from the glass, and the operation is complete. The gelatin sheet of varying thickness thus produced can now be used as an overlay.

It will be observed that in both the methods above described we proceed photographically to produce from a print or impression of the engraving, cut, or printing-plate a photoprint or photograph which instead ol being expressed in varying degrees of shade or color, as usual, is expressed in varying degrees of thickness. In both methods we rely on the well-known quality of bichromated gelatin, that of becoming insoluble on exposure to light, as the means for attaining the variations of thickness. In the first method the most exposed portions answer to the high lights, and those portions on soaking the gelatin do not swell, so that the varying thicknesses of the swelled-gelatin plate are such as are required in the overlay, and the purpose ot' making a plaster matrix is to render the variations of thickness permanent, since the swelled-gelatin plate is incapable of use as an overlay, and even if so capable its varying thickness would chiefly or wholly disappear on its becoming dry. By the second method described the most exposed portions ol the gelatin answer to the dense shadows or solid black of the print, and in the operation of dissolving off the gelatin it is gradually reduced in thickness where least exposed, leaving the most exposed portions of the original thickness until a sufficient difference in thickness is developed to answer the purpose of an overlay. The gelatin sheet thus produced may be itself used directly as the overlay, because when dry it preserves the requisite variations of thickness; but in case IIO two or more overlays for the same engraving were required they could be readily reproduced from this gelatin plate by the same process of molding in a matrix as first described, or in case some more pliable and yielding material than gelatin is desired for the overlay such reproduction could be made for that reason, or by a modification of this second method the gelatin instead ol. being exposed under a negative might be exposed under a positive print, and then by dissolving away the exposed gelatin sheet until the required differenees in thickness are developed the gelatin may be used as amatrix in which may be formed from any plastic material the required overlay. Similarly, bya modification of the first-described process by using a negative print under which to expose the sensitized gelatin the latter after exposure maybe swelled and then remaining swelled may be used as a matrixin which to cast or form the required overlay. Our invention thus includes all these several methods and generally comprehends any mode of producing an overlay by developing from a print, engraving, or reliefplate a photograph the variations in depth of tone of which shall be represented by variations in thickness, the differences of thickness being in such proportion as is required by printers for making a practical overlay. In this specification wherever we have referred to the print77 under which (or under a negative from which) the sensitized gelatin is exposed we do not necessarily mean to confine ourselves to a printed impression from the relief-plate or engraving, since a printed iinpression or photograph from the original artists drawing, or in the case of a photo-plate or half-tone engraving a printed impression, photographic or otherwise, from the original drawing or photograph from which the reliefplate has been made, will answer the same purpose, or a negative of either of these may be used.

The printers overlay produced by our invention, whether made of gutta-percha or other material, has the advantage of being homogeneous as distinguished from being built up of layers, as with overlays heretofore made.

We claim as our invention the followingdefined novel features, substantially as hereinbefore specified, namely:

l. A printers overlay consisting of a sheet of homogeneous material corresponding to a relief-plate to be printed from,varyin g in thickness in different parts in approximate proportion to the variations in depth of tone in the print from said plate, being thickest in coincidence with the solid black portions, thin-` nest at the high lights, and graduated in thickness between, substantiallyas set forth.

2. A printers overlay consisting of a photograph of a print from the relief-plate to be printed from, said photograph varying in thickness in proportion to the variations in depth of tone in such print, substantially as set forth.

3. The improvedmode ofpreparingaprinters overlay for printing from a relief-plate or engraving, which consists in photo-exposing a sheet of sensitized gelatin beneath a positive or negative answering to the impression from such relief-plate, and subsequently treating the exposed gelatin with Water to develop variations in thickness therein corresponding to the variationsin depth of tone in the prints to be produced from said relief-plate.

4. The described process of preparing a printers overlay for use in printing from a relief-plate or engraving, which consists in exposing a sheet of sensitized gelatin beneath a positive print or impression corresponding to such relief-plate, soaking the exposed gelatin in water to swell the soluble portions thereof, and -thereby develop differences in thickness', then preparing a matrix of such swelled-gelatin sheet, and forming in such matrix an overlay duplicating the variations in thickness of said swelled gelatin.

In witn ess whereof we have hereunto signed our names in the presence of two subscribing Witnesses.

EDWARD BIERSTADT. THEODORE B. DE VINNE.

l/Vitnesses ARTHUR C. FRAsER, GEORGE H. FRASER.

Images