USRE5961E - Improvement in photolithography - Google Patents

Description

UNITED STATES PATENT OFFICE.

,J'o-nn WALTER OSBORNE, or wAsHINeToN, nrsrnror or COLUMBIA, AS-

s onon, BY Mnssn AssIe-NMENTsTo run AMERICAN rnorotrruo. GRAPHIC COMPANY, or NEW YORK orrr.

IMPROVEMENT IN PHOTOLITHOGRAPHY- Specification forming part of Letters Patent No. 352,668, dated June 25, 1861; reissue No. 6,961, dated July 7, 1874; application filed May 16, 187 i.

To all whomit may concern.

Be it known that I, JOHN \VALTER ,Os-

BORNE, formerly of the city-of Melbourne, in

the county of Bourke and Colony of Victoria,

. Australia, but now residing in the city of .Vaslnngton and District of Columbia, have invented or discovered certain new and useful Improvements in the Art ofPhotolithograph y; and I do hereby declare that the following is a full and exact description thereof.

The object of my invention is to produce by photographic means, upon plates or lithographic stones, designs or pictures from which impressions can be taken with printing-inkin usual;well-known ways.

'Iaa ceomplish this object I avail myself of the 'alterative action of light upon certain kinds of organic matter- -such as albumen and gelatinein the presence of bichromate of potash; also, of the strong aiiinity which organic matter thus altered has for greasy ink, and of its repulsion for water; also, of thecapacity which unaltered gelatine has for absorbin g water, which gelatinizes and swells it; also, of the fact that heat and moisture, conjointly, willafl'ect the coagulation of albumen,

thereby converting itinto an insoluble substance possessing a film-likeor membraneous structure, and adhesiveness under pressure; and I also employ certain general principles and particular manipulations well known to photographers, lithographers, and printers in the copying, transferring and treatment of thework. My invention consists in certain novel improvements in the art, method, or process to which they relate. The subjectmatter claimed is herein after speci fically desi gna tedp.

' To enable others skilled in the art of photoli'thogr'aphy to make fnsewof my invention, I

*will, proceed to describe how the process may beperformed. I p

- I first make a solution of the lbllowing 1ngredients in about the )l0')Ol'tl0l1S hen which are those I prefer to employ, viz Albumen, two ounces; gelatine, eight hundred grains; bichromate of potash, four hundred andforty grains water, eight ounces.

The gelatine and the bichromate (thelatter and well mixed, and the whole allowed to re-- pose for a time. The albumen should be obtained from fresh eggs, whipped to a froth, allowed to subside, and the quantity required then be measured off. I then take a sheet of plain positive photographic paper, dampen it, and, when it has become quite flat,cover it on one side with the solution above mentioned.

To apply this solution to the surface of the paper, the following or any more convenient method may be adopt-ed Lay the paper, face down, on a board, near one end of which is adjusted a trough, containing the mixture before mentioned, cooled to the tem-peratin'e of 85 Fahrenheit; The side of the trough nearest the paper should be rounded to pre- ,vent undue friction. The trough should be provided with amovable piece of wood, passed longitudinally through it, with a rounded ed go, under which the paper is drawn, which piece ofwood should'be so adjusted as just to press the under surface of the paper into the bichromate mixture as the paper is d awn under the rounded edge of the same upward from the trough;

The bichromate solution or mixture hereinbefore described may be varied as to quantities, or by the substitution or addition .of

other ingredients, such as chromic acid, or

any other chromate or bichromate, or anyof the salts of uranium or other chemicals-of similar properties, so far as such can be used without impairing the advantages arising from a preponderance of albumen, or interfering with the characteristic property possessed by gelatineof swelling in coldwater. I

The photolithographic transfer-paper, the manufacture of which has been described, may

also, with equallygood results, be prepared by coating the plain paper with two solutions,

the first to consist of one part albumen, with I potash, three hundred and fifty-two grains.

In whichever of the ways above described the photolithographic transfer paper is made, it should be dried in a perfectly dark and warm room, and then passed through a lith0-' graphic press upon a copper plate, in order to glaze and flatten it.

A negative of the object to be photolithographed is now to be taken, and the sheet of paper, prepared as above,,to be exposed under it, in a photographic pressure-frame used for nniking positives in sunlight, from one-half minute to six minutes, or more, if necessary.

This photographic positive-print is nextto be inked in by passing it in its dry condition through a lithographic press, with its face toward a lithographic stone or plate, said stone or plate having been first evenly rolled inwith lithographic transfer'ink. When the paper is pulled off the stone the greasy ink should be found to be of such a thickness as to disclose the positive-print dimly through it.

The next operation is an important part of my invention. Its object is to effect the coagulation of the albumen combined with the sensitive. coating. With this in view, the inked print should now be taken into a darkened room and placed (swimming) on boiling water contained in a tray or dishlthe inked side upward, excluding air-bubbles--where it should be left until the water is cold. A distinct-ive feature of my process is, availing myself of the swelling properties of gelatiue, which change is brought about in the sensitive coating simultaneously with that of the coagulation of the albumen while the paper is swimming upon the water. The efi'ect of these swelling properties of unaltered gelatine is to cause the altered portions of the gelatine, which do not swell, to become relatively depressed, whereby the ink upon said depressed parts is protected during the washingoff process, which is done as follows:

The print is to be placed, face upward, upon a smooth board, and washed off gently with a clean soft sponge dipped in water. When the print is clean enough, pin it fast to the board; pour a large quantity of boiling water over it from a kettle or other vessel. Now remove it-from the board and lay the print, face up, on the boiling water, and let it float until the upper surface is dry, which soon takes place if the print be surrounded with an inky border. When the albumenized surface is dry; lift the paper off the water, lay it on blotting-paper, and then finish drying in any convenient manner. I This transfer-sheet may now be transferred to a lithographic stone in the ordinary way,

.or to the surface of a zinc plate, for zineographic printing; or to a copper plate, to be used as a guide for engraving on copper; or

to any surface of wood, metal, stone, paper or cloth, glass, iudia-rubber,-leather, or guttepereha.

M y process or method differs materially from that described in Newtons or Cutting & Bradfords patent. By Newtons process the photographic picture is thrown upon a litho-,

graphic stone or zinc plate prepared for the purpose by a direct exposure under a positive, or in the camera, and theink adheres eventually to those parts of said prepared surface where the light has not acted whereas I do not work upon the stone or zinc direct, but upon'a prepared surface upon paper,.whereby a positive transfer is made, upon which the ink will be found adherent to those places where the light has acted. By Newtons process it will be found difiicult, ifnot impossible, to produce. the clearness and sharpness requisite for printing maps, line-engravings, drawings, and manuscripts.

- Poitevin produces his photolithographs upon the stone direct; in this he differs from me, and also in his method of wetting the exposed surface of his sensitized paper for the production of a carbon print before inking it; whereas I, on the contrary, ink my transfersheet while dry.

Assers process differs from mine in the nature of the basis over which the sensitized coating is applied. He uses plain paper, or paper sized with starch, while in my process the existence of a coating of albumen under the work prevents the greasy ink from spreading into the fiber oi pores of the paper, which would injurethe clearness of the lines. Ass'er also washes and wets his exposed transfer sheet before inking it.

Colonel 'Jamess method, practiced in the BritislrOrdnance Survey Office, also differs from mine, inasmuch as he uses gum in preaction of the boiling water, every attempt to wash it away. This invention is also subsequent to mine. The work, therefore, is found eventually to be upon albumenized paper, which, besides improving its quality, plays a very important part, by constituting an underlying adhesive coating, which adheres firmly to the lithographic stone or other sulstauce during the operation. of transferring in, the lithographic press, in consequence whereof the paper cannot slip, which would, cause the work to become thickened or doubled. The compound film of albumen and gelatine, upon which I work, enables me also to derivegreat adi' antages from the manner in which those parts of it unacted upon by light swell up when floating the inked print upon the boiling water; this change in the exposed and inked surface causing the work to become co nsiderably depressed, whereby the inksupon it 'alnl-clearncss is the result.

. of said paper.

is protected from the rubbing action of the sponge, and thenraxnnum amount of firmness my process differs materially from Colonel J amess, and all others. 1

. From thefbregoin references, it .will be seen that I do not claim tobethe original inventor of photo]ithography.

I am aware that the sensitized surfaces of lithographic stones and metal plates have been inked while dry, and do not, therefore, broadly claim the dry inking of any and every surface for pliotolithographicpurposes; but I. am not aware, and do not believe, that prior to .the date of my invention a sheet of 'p'hotolithographic transfer-paper was ever inked while dry with lithographic transfer-ink after the formation of a picture on the sensitized surface [am likewise aware that ink has been applied to the whole sensitized surface of a lithographic stone after the same has been exposed to light for the production of a design thereon, and the superfluous portions of ink subseqnei'ltly removed but 1 am not aware, and (lo-not believe, that prior to the date of my invention an exposed sheet of pl|iitolithogra-phic transfer-paper has been uniformly inked with lithographic transferink, and the excess (not required to form the design) subsequently removed in any way, or by any means whatsoever.

1 am aware that prior to the date of my invention the swelling property of gelatine had been made available for the product-ion of relief and intaglio plates but I am not aware, and do not believe, that prior to the date of my invention the swelling and gelatinizing properties of gelatine were used to facilitate the removal from the sensitized surface of a sheet of photolithographic transfer-paper of superfluous ink thereon not needed to form the transferable picture.

1 claim as my own invention- 1. The improvement in the art of preparing photolithographic transfecpa-per herein set forth, which improvement consists inthe application to the surface of a sheet of paper of a mixture of albumen, gelatine, and bichromate of potash, substantially as hereinbefore set forth.

2. The improvement in the art of inking photolit-hographic transfer-paper herein set forth, which improvement consists in hiking with lithographic transfer-ink photolithographic transfer-paper which has been exposed 10 light for the production of a picture or design thereon, and while said transfer-paper is in a dry state, substantially as hereiubefore set forth.

3. The improvement in the art of inking photolithographic transfer-paper herein set forth, which improvement consists in inking with lithographic transfer-ink the entire coated surface of a sheetof photolithographic transfer-paper previously exposed to light for the production of a picture or design thereon, substantially as hereinbefore set forth.

In this respect 4. The improvement in the art of photolithography herein set forth, which improvement consists in inking the coated surface of a" sheet'of photolithographic transfer-paper, (pi eviousl y exposed to light for the production of a picture or design thereon,) and then reniovin g therefrom the snperfluons'ink not needed to form the transferable picture, substantially as and for the .purposeset forth.

5. The improvement in the art of removingphotolit-hographic transfer-paper ink from herein set forth, which improvement consists in removing the superfluous ink (not needed,

to form the transferable picture) from, the surface of a sheet of inked and exposed photolithographic transfer-paper by the conjoint action of friction and moisture, suliistantiall y as hereinbeforc set forth.

6. The improvement in the art of preparing photolithographic transfer-paper herein set forth, which consists in providing the paper with a. film of coagulated albumen, to prevent the smearing of the fibers of the paper by the greasy ink, substantially as set forth.

7. The improvement in the art. of photolithography herein set forth, which consists in coagulating by heat and moisture the albumen in the coating'of a sheet of photolithographic transfer-paper which has been exposed to light (to produce a picture or design thereon) and inked with lithographic transfenink, substantially as hereinbefore set forth.

S. The improvement .in the art of phot lithography herein set forth, which improvi ment consists in preparing a. sheet of photolithographic transfer-paper by coating its surface with albumen, gelatine, and bichromate of pot ash; exposing it tolight to prod ucc a picture or design thereon; inking this sheet with lithographic transfer-ink; coagulating the albumen by heat and moisture to produce a homogeneous insoluble coating, covering the paper,

and underlying the picture; and removing the superfluous ink (not needed to form the transferable picture) from those parts unaffected by light, substantially as hereinbefore set forth.

9. The improvement in the art of photolithography herein set forth, which consists in the application of moisture to the gela-tinecoated surface of a sheet of photolithographic transferpaper which has been exposed to light to produce a picture or design thereon, and then inked when dry, whereby thegelatine is gelatinized and swelled, so as to lessen the adhesion of those parts of the coating unaffected by light, and elevate them above the altered parts, thus facilitating the removal of the ink from the parts unaffected by light, substantially as hereinbeforc set forth.

' 10. The improvement in the art of photolit-hography herein set forth, which consists in moistening, through the back of a sheet of photolithographic transfer paper, a gelatinecoated inked picture, whereby the gelatine is gelatinized and swelled, so as to raiserthe parts of the coating unaltered by light above the altered parts, thus protecti-n them, while facilitating the removal of the ink from the unaltered parts without inoistening the coating through the ink. j

1]; I'lheimprovement in the art of photolithography herein set forth, which consists in inkingthe albumen coated Sillfz'tGG ot'a sheet of 1)hotolithographic transfer-paper which has been exposed to light for the production of a picture or design thereon, coagulating the albumen,. removing the ink from the parts unaffected by light, placing the inked sheet 011 a stone for transfer, and pulling the sheet through the press, whereby I am enabled to avail. myself of the adhesivcncss of the coagulated albumen to the stone to preventthe moving of thetransfer-sheet thereon while the transfer is being made, substantially as hereinbefore set forth.

12. The iniproven'ient in the art of photo- 'lithography herein set forth, which consists in washing the coated surface of a sheet'of photolithog'raphic transfer: paper with hotJw-ater to remove soluble matter therefrom after the removal of the superfluous ink, substantially as hereinbefore set forth.

15. The improvement in the art of photolit-hogra-phy herein set forth, which consists in rcoatinga sheet of paper with a mixture of albumen, gelatine, and bichroniate ot' potash,

"exposing it to light to produce a picture or design thereon, inking the sheet with'lithographic transfer-ink, and then moistening' the sheet through the back in order to gelatinize and swell the gelatine unaffected by exposure to light, whereby those parts are raised above the altered port-ions of the picture, thus protecting the altered portions and facilitating the removal of the unaltered parts.

14. The improvement in the art of photolithography herein set forth, which consists in preparing p'hotolithograpliic deli neations from which impressions can be printed, after the manner of lithogmphy, by coating a sheet of photolithographio transfer-paper with albumen, gelatine,'and bichroniatc of potash, exposing it to light to produce a picture or design thereon, inking the whole surface of the coated sheet while dry, exposing the inked sheet to heat and moisture to coagulate the:

albumen and swell those parts of the gelatinized surface unaffected by light, removing the superfluous ink not needed to form thcpicturc by the conjoint action of friction and moist- .ure, and transferring the inky picture to the lithographic stone, substantially as hercinbe' fore set forth.

JOHN \VALTER OSBORNE.-

Vitnesses: WM. 1). BALDWIN, J on I. PEYTON.