US159166A - Improvement in processes of preparing gelatine-plates for printing - Google Patents

Description

UNITED STATES PATENT OFFICE;

' ERNEST EDWARDS, OF BOSTON, MASSACHUSETTS, ASSIGNOR TO JAMES R.

OSGOOD, SAME PLACE.

iMPROVEMENT lN PROCESSES 0F PREPARING GELATlNE-PIATES FOR PRINTING.

Specification forming part of Letters Patent No. 169,166, dated January 26, 1875; application filed April 27, 1874.

I To all whom it may concern:

- sorbent by certain well-known means, such asthe formation of chromic acid,by the aotiqn of light upon bichromatized gelatine, or by the application of chrome-alum or tannin. In previous applications of this principle, those p0r-' tions of the gelatine which by such means are rendered non-absorbent have been used, by various devices, to produce tlne print or picture. I have discovered, however, that those portions of the gelatine whichafter such treatment remain still absorbent may also be used to produce a print or picture, by causing such remaining absorbent parts to absorb or tak e up a quantity of water containing in solution any convenient color or dye. It will be readily understood. that, by placing paper or other suitable material on such a surface, and applying sufiicient pressure, the paper or other material will receive the color from the gelatine-plate in just such proportion as the gelatine has been allowed to remain absorbent.

My invention consists in produeingimpressions with colors known as dyes, as distinguished from printing-inks, from plates consisting of gelatine, gum, albumen, fibrine, or analogous substances which are absorbent of water,-the parts which are not required to print having'bee'n rendered non-absorbent of water, or otherwise suitably prevented from printing.

I will describe the mode by which I have successfully prepared and printed from such plates according to my said'invention.

Upon a suitable surface of metal, wood,

stone, glass, or other suitable material, I place a layer of gelatine, gum, albumen, fibrine, or analogous substance, on-which an image has been or is to be produced, by rendering such portions as are not required to print non-absorbent of water by any of the well-known means. In preparing the gelatine or equiva lent plate, I have found the following to be a convenient formula: I take of gelatine, one ounce; water, six ounces; .bichromate, thirty grains. I dissolve the gelatine and bichromate in the water, heated for the purpose, and spread the mixture upon a surface of slate. When dry the plate is to be exposed to light under a photographic] positive, (as distinguished from a negative.) After an exposure suificient to render non-absorbent those parts not to be printed, the plate is washed with water till all bichromate has disappeared. It 7 In place is dried, and is then ready for use. of a photographic pbsitive a design or tracing may be used, or the bichromate may be omitted and a design drawn directly on the gelatine (or transferred thereto) with chrome-alum. Or a design may be drawn or transferred to the gelatinein an opaque or water-proof varnish, the portions of the gelatine not covered with the varnish being then renderednon-absorbent; or a stencil-plate or mask maybe used, so as to, mechanically prevent the portions of the gelatine covered by it from imparting any of the solution in those parts to the paper on which the impression is to be made.

Impressions may be taken from the plate prepared as above described in the following manner: The surface of the prepared gelatine or equivalent plate is to be wetted or dampened with a solution in water of the desired color, and the surplus moisture is to be removed. by any convenient means. The paper or other material on which the image is to be printed is then to be pressed upon the surface of the plate, so as to receive a portion of the color.

As the colors to be used in this kind of printing and 'known as dyes are soluble in water, and as these colors are to be applied to I the surface of the plate in solution, they will not be absorbed by the parts of the plate which have been rendered non-absorbent of water, but in the other portions they will be absorbed just in proportion as the absorbent property has been modified by the treatment which the gelatine has received. \Vhere the colors used are dyes which require mordants to strengthen the color, the dyes and mordants may beapplied in any convenient manner or order. Care must be taken, however, to use only such dyes or mordants as do not injuriously affect the 'gelatin'e, plate. The following are convenient formulas: First. Mordant to be applied to the paper: Solution of photo-chloride of tin,'one part; water, nine parts. For wetting or dampening the gelatine plate, a saturated solution of extract of logwood.

Second. A saturated solution of aniline-purple, used alone, or with amordant, where necessary, of perchloride of tin.

Third. Chloride of cobalt, one part; water, ten parts.

The image in this case does not appear till heat is applied. On cooling it disappears, and

heat is always necessary to redevelop it.

My said process is also applicable to printing on fabrics, and on all other. material suitable for receiving the action of dyes.

What I claim as my invention, and desire to secure by Letters Patent, is-

The described process of printing from plates of gelatine, gum, albumen, and other analogous bodies which are absorbent of water, with soluble colors known as dyes, in contradistinetion to those known as printing-inks, the parts not required to produce an impression'having been previously rendered non-absorbent of Water (and hence incapable of printing) either by exposure to light, the application of a coagulating substance, an opaque varnish or mat, or other suitable means, substantially as specified, and for the purpose set forth.

ERNEST EDWARDS.

Witnesses:

WALTER RowLANDs, K; L. BERGSTROM.