US1453259A - Printing plate and process and composition of matter for forming the same and process of printing - Google Patents

Description

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nonnnr man, or new roan, n; r.

:1 l l lam THE aaarn AND PROCESS OF PRINTING.

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To all whom it may concern c Be it known that l, ROBERT, dorm, a citinon of the United States, a resident of the city of New ltorlr, in the county of New t lfork and State of New York, have invented certain new and useful Improvements in Printing Plates and Processes of and Compositions of Matter for Forming the Sallie and Processes of Printing, of which the fol- 1 lowing is a specification.

My invention relates to printing plates and processes of and compositions of matter for forming the same, and has, among other objects, the following: first, the production of a plate, and particularly a lithographic plate, and more particularly of a plate such as is used in photo-gelatine printing processes, and a process of printing by which plate printing press prints or repro- 2 ductions may be made of a quality superior to any hitherto known in the art; second, the production of such a plate by which such prints or reproductions may be produced at a speed greatly in excess of any tt hitherto possible in the art; third, the derising of a process by which a printing plate may be produced with less labor and expense and in a shorter time than has hitherto been possible in the art, and fourth, t0 the production of such a plate which shall reduce the loss of time arising from press stops to a hitherto unattai'ned minimum; and to suchends my invention consists in the improvement in printing plates and 35 processes of and compositions of matter for forming the same and processes of printing hereinafter specified.

ll/ly invention is capable of embodiment in many diderent forms of plates and proct0 esses of producing such plates and of printing and by the use of various compositions of matter in such production, and. while ll shall choose. for the purpose of illustrating my invention. the best embodiment thereof t5 known to me, such embodiment is to be regarded only astypical and my invention is not to be confined thereto.

The example chosen for illustration is designed for use on a litho-off'set printing 50 press. I may use as a base or backing for the plate. thin plates formed of metal, such as aluminum or zinc. ranging in thickness,

' for example, from .01 to .03 inches, or T may use other materials, such as a sheet of m pyroxylin, pyralin, or celluloid for such application filed August 16, 1922. Serial No. aaaaar.

purpose. For the illustrative example, a metal plate is chosen, and the first step is to produce a grain or roughness on one side .of the plate for the purpose of increasing adherence of the gelatine coat thereto which ll next put on it. For this purpose ll preferably effectv a graining equivalent to that of fine mudground glass, preferring that the grain should be as fine as possible and merely presenting a rough surface. It is to be understood that, as the said graining is simply for the purpose of securing" the gelatine coating to the plate, it does not appear in the imprint from the plate and has no effect thereon as would be the case with the grains which are produced on ph0to-lithographic or offset plates for the purpose of breaking up the continuity of the photographic image.

lhl'aving produced a grain upon my plate and thoroughly cleaned it of grit and metallic particles. as by a water spray, ll apply the coat of gelatine thereto in any desired manner. as by whirling it with a solution of gelatine. A suitable solution for the purpose may consist of water, 32 ounces, and hard commercial gelatine, 2250 grains. the gelatine having first been soaked in cold water and then brought into solution by raising the temperature to 120 F. The gelatinous solution thus prepared is applied on the center of the grained plate, while the latter is whirling at a rate, say of approximately 20 revolutions per minute, the temperature being preferably maintained at 120 F. under which conditions a proper thickness of coating is obtained. For my purpose T prefer a coating measuring ap proximately .0008 to .0012 inches in thickness. The plate is preferably permitted to whirl until it is dry. I

l'laving coated my plate and preferably dried it. I preferably subject the gelatine to a hardening agent, such as a bath consisting of alcohol. 32 ounces, and formaldehyde, Wt 40 1 ounce. to which the plate is subjected for five minutes. The plateis then preferably again dried as in an enclosed Whirler for five minutes and subsequently washed in cold running water for five minutes, when Wt it is again preferably dried, as by whirling. The plate is now ready for the preferably next succeeding operation, which is that of sensitizing. l find that plates thus coated keep indefinitely without deterioration and lltl tltli till ltd

I am, therefore, able to coat and harden them in quantities and have a supply alwa s on hand ready for sensitizing.

aving coated and preferably hardened my plate, I sensitize it by a composition which, directly or indirectly, will render the gelatine selectively receptive to a printing medium such as ink. In the present instance, I sensitize the plate by immersion for two minutes in the following solution:

Water 16 ounces Alcohol 32 Ammonium bichromate 450 grains Water 16 ounces Alcohol 32 Ammonium bichromate 450 grains Erythrosine 90 Theplate being sensitized, is ready for exposure to light behind a negative (or a positive) and, as in the case of most chromatized colloids, I find it desirable to effect exposurc as soon after sensitizing as possible inasmuch as deterioration soon sets in.

If, after having performed the above described steps, I were to wash my plate in cold running water, I would find that those portions of the plate affected by light were harder than those portions unaffected by light. I, however, do not wash the plate at this stage of its preparation as would be done in other processes. While, in my plate, at this stage there is a difference between the light-affected areas and those unaffected by the light, yet that difference is insufficient to enable the plate to receive ink selectively.

Having effected the exposure under the negative, I next proceed with the steps which give it its great selective ink receptivity, as well as its later durability. For this purpose I desire to selectively lncrease the hardening action which has been started by the light in the chromatized colloid, and

to do so without equally hardening the colloid in its unaffected areas. 7 I preferably use as a hardening agent a substance which, when the excess of such agent is removed,

. leaves the light-affected portions of the film,

and preferably the entire surface of the film, in a dry state. I further prefer to use a hardening agent which also is not absorbed by the film. Therefore, having exposed my plate, and preferably without havin I washed out the unaltered bichromate, I pre erably subject it immediately to a hal'denaffected portions.

Preferably after again washing the plate, I further harden the'hardened rtions, as by placing the plate in a bath ofgure grain alcohol of high proof for two minutes. I find that although the unhardened portions are water-soaked, they are not materially affected by this treatment, since the ammonium salt has been washed out. After this second bath of alcohol I again dry the plate, preferably by whirling, whereupon it is ready for the last step in its preparationnamely, that of heating. This is effected by placing the plate in say, for three minutes, an oven in which, for instance, a temperature of approximately 400 F. is maintained. I-find that the effect of. the heating is twofold; first, the heat completes whatever chemical action has been started between the gelatine and bichromate thro h light exposure and the alcohol, and iereby materially hardens the light-affected areas and brings the plate to a point where there will be no further hardening effect even though the plate be kept for months, since all the chemical action is complete, second, I find that heating as described has the effect of toughening the unaffected portions of the gelatine without materiallyreducing their water receptiveness, andat the same time increasing the degree of adhesion between the gelatlne coating and the grained metal plate.

When the heating operation is complete, my plate is ready for the press and, when fastened thereto, requires only moistening by water by such means as are to be found on litho and offset presses to be a completed printing plate.

When ink is applied to the wet surface of my plate in printing, I find that, in effect, the ink is emulsified with the water and that a very effective printing results therefrom, the ink being so readily deposited on a print, or on a rubber blanket, as in offset printing, and redeposited therefrom upon the print or final support that, not only are prints of 1 high quality obtained, but they are produced at a much greater rate than has ever been done before.

My invention, while having some similaritics to other printing processes, has marked differences from and advantages over any of them whichare known to me. I shall refer t it till

na-aaata particularly to photo-lithography, photoobtainable. by my invention in a printing" press is markedly superior to those obtainable in that manner by any'other process known in the art, including those just ret'erred to, and the rate oil production is also much above that possible with such prior art. By my invention torty times as many prints can be made in a given time as with the pre vious photo-gelatine processes.

lln all photo-gelatine processes prior to mine, it has been necessary to term a grain or reticulation in order to create a sutticient selective ink receptivity to attain commercial results, but it is not necessary to use that expedient with my invention. lit has also been necessary, prior to my invention, to treat the photo-gelatine plate with a glycerine solution in order to increase said selective ink receptivity. But my plate may be used smooth and efrainless, and l employ plain water in moisteninp; it before inking, no glycerine or other agent for swelling the gelatine being; required.

,lt is to be noted that in the present example a chromic acid salt is incorporated intmy film by first torming the gelatine film on the plate and then atterwards introducing the chromic acid salt by bathing, the film in a solution of such salt, and when a film is thus formed, it will not become reticulated even though in the'previous dryinn it had been dried at a temperature which, it the salt had been incorporated with the grelatine while the latter was in solution, would cause reticulation,namely, a temperature approximating or above 130 h. l can, however, incorporate, the chromic acid salt in the film. by introducing'it into a solution ot the ,qgelatine before the latter-is depositeld upon the plate to form the film, by evaporation of its solvent, and still obtain a film that is tree from reticulation, so long, as l[ do not heat it above 130 F.

While the portions of my colloid film which have not been afiected by light are so receptive to water that they pertectly reject the ink without the aid of any other expedient than moistenina', the portions of the film whichhave been affected by light and which i are to receive the ink to term the image still till possess some capacity tor absorbing; water,

and this capacity, in co-operation with the other qualities riven to the light afif'ected portions by my said treatment, in some way repders such portions unusually receptive to in it.

Because, therefore, of the tact that l print trom a wet ink-receptive surface, while the phot -lithe and pheto-ofiset pla es are printed with a dry ink-receptive surface, l are able todeposit on the finished print a quantity of color impossible with such processes, and am therefore enabled to print at much greater speeds than their plates permit. Furthermore, li eficct a noteworthy saving in press operation through the fact that, while the photo-litho and photo-offset plates have a tendency to oxidize in the air and to lose their water receptivity, which makes necessary. at frequent intervals. a certain operation known as summing, my plate cannot oxidize and requires no gulnniing, and in no way increases the number or duration of press stops. In other words, with my plate, it is not necessary to stop the press for grummingr, or for any other operation to renew the selective receptivity of the plate to the ink which forms the print, as such selective receptivity depends only on the presence of the water, and this is automatically renewed after each impression from the plate and without any stoppage of the press.

Referring to the marked superiority in quality of prints and reproductions made accordin to rev invention as com ared with the quality of those made by the three printing processes above mentioned: ltn the photopelatine process, there is of necessity a grain or reticulation, finer or coarser, which is inherent to the formation of the plate.

from grain and reticulation may receive its image either trom a continuous tone negative or from a negative made from a halttone screen or from one in which any manner of dot, grain, or particle is employed.

The plates used in the photo-lithe and photo-ofi'set processes must of necessity be made from negatives embodying a dot or grain. On the other hand, my plate, printed on the same press, may be absolutely con tinuous in tone and tree from dot or grain, or, it desired, it may embody a dot or grain, which may be very much finer than any other grain hitherto capable of use in the said process. With my process, l have tound it practicable to use dots which were sin times as many to the inch as the most that have been. used in photo-lithe and photo-otlset processes, so tar as l[ am aware. For instance, in practice it has been found that a dot averaging to the inch produces the best results in photo-litho and photo-offset printing, and, while dots as fine as to the inch have been employed, they have not been deemed commercially practicable or come into general use. With my plate, however, under commercial conditions I have found it practicable to use a dot as line as 400 to the inch and a grain as fine as 1200 to the inch.

liltt The degree of fineness of the dot or grain which it is possible to use with my plate is limited only by the ability to .produce a screen bearing them. \Vhile, in theory, a continuous tone image such as my plate alone is capable of rendering is theoretically desirable, yet, due to inequalties of paper surface and other commercial factors, 1 find it usually preferable to employ a very fine screen or grain, but it is characteristic of my plate that its wearing qualities and its ability to give continuously perfect reproductions are not influenced, one way or the other, by the fineness of the dot or grain used. I

A suitable way in which to form dots upon one of my plates is to form them on the negative, fromwhich the plate is to be printed, in a camera in the manner in which dots are formed in the well-known half-tone process, where the dots are formed by focusing a screen, either regular or irregular, between the lens and the sensitive plate.

A suitable way in which to form grain or reticulation on one of my plates is by printing from a negative made as described in my United States Patent No. 1,374,853, April 12 1921.

in all reproductive processes, other than mine, wherein a screen, either dot or grain, is used whether in photo -engraving for relief printing or photo-offset or lithography for photographic printing, a number of steps are involved in the process which forbid the use of a dot or grain as fine as that which I can employ. These steps are those intermediate between the exposure of the colloidal bichromated surface to the light and the actual inking of the plate on the press. They involve, for instance, developing away unexposed portions with water and cotton wool, rubbing up with ink or acid resist, etching, re -etching, etc. No matter how careful the manipulations, these operations would change the character or formation of the dot or grain, if one were present as fine as I am able to use, so that much of the result accomplished by exposure to light would be lost when the printing plate was finally inked.

In my process, there is no change in the surface of the plate between its condition when exposed to light and its condition when finally inked to make an impression, and there are no manipulations that can possibly change the size, shape, or character of the dots imprinted by the light. I believe, in fact, that'I am the first to produce a printing plate capable of taking ink on a printing press on which the impression is to be formed in which the dots or grains produced by light action are unaltered by manipulations of any kind; such as, reticulation, development, etc., previously mentioned. I further believe that I am the first to prepare a printing plate wherein the ink image corresponds exactly to the action of the light in the exposure.

A printin plate made accordin to my invention wil receive ink selectively as to its light affection from a roller passed over its surface at a much higher speed than will any other photo-gelatine plate or plate having a colloid film with which I am familiar. With my plate, the ink-applying roller may be passed over its surface at a speed greater than six inches per second.

In my process, as the portions of the plate which are to print the image are moistened with water before ink is applied to them, and are at all times both water-receptive and charged with water, and as, when ink has been applied to such portions, the wa ter and oil do not separate into distinct bodies when heavy pressure is applied between the plate and the paper or rubber blanket upon which the impression is to be lieve this condition explains why my plate will print with so greatly increased a speed. This emulsification of the ink and water I regard as very important and believe it to be a strong factor both in obtaining the relatively great density of color which the plate will print and the high speed with which it will print.

By the term mechanical inking, as used in the claims is meant inking by the more use of a mechanically-operated roller or other device as distinguished from rubbing, stipplingwith a brush, or rolling by hand, or other manual operation.

Bythe term chromic acid salt it is meant to include every compound of chromium having the property of more or less hardening organic matter under the action of light.

Many modifications of my invention can be made without departing therefrom or from the scope of the claims, and my invention is not limited to the particular embodiment chosen for the purpose of illustration.

Haying particulary described my invention, what I claim and desire to secure by Letters Patent is:

1. A printing plate comprising an unreticulated colloid film which is capable of printing after mechanical inking.

2. A printing late comprising an unrej at llll

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tgttaatt ticulated gelatine film which is capable of printing at'ter mechanical inking.

3. A printing plate comprising a colloid film which is capable of printing after mechanical inking without the use of glycerin or other similar swelling means.

4:. A printing plate comprising a gelatine film while is capable of printing alter mechanical inking without the use of glycerin or other similar swellingmedium.

5. A printing plate comprising a colloid film having dots or grains photographed thereon which in the finished plate are unaltered from the form in which they were originally photographed on such plate.

ti. A printing plate comprising a gelatine film having dots or rains photographed thereon Which in the finished plate are un altered from the form in which they were originally photographed on such plate.

A printing plate comprising an unreticulated colloid film having ink-receptive portions that are interrupted by relatively very fine dots, or grains, or similar devices.

8. A printing plate comprisin an unreticulated gelatine film having inlrreceptive portions that are interrupted by relatively very fine dots, or grains, or similar devices.

9. A printing plate comprising a colloid film having ink-receptive portions that are interrupted by dots, grains or similar devices that are photographed thereon.

10. A printing plate comprising a gelatine film having ink-receptive portions that are interrupted by dots, grains or similar devices that are photographedthereon.

ll. As an article of manufacture, a photogelatine printing plate having the ability to take on ink selectively as to its light aection from an inking roller passed over its surface at a rate exceeding six inches per second.

12. A planographic printing plate capable of receiving ink selectively as to its light affection, from a roller passed over its sur- 1 face at a speed greater than six inches per till lltl

second, in which the portions of the plate unatlected by light are composed of a collo-id.

13. A planographic printing plate capable of receiving ink selectively as to its light affection, from a roller passed over its surface at a speed greater than six inches per secend, which comprises a colloid film, all of the original colloidal material of 'the film being present in the portions of the finished plate unafiected by light.

ll. A printing plate in which the ink-recaptive image is composed of an unreticulated colloid that is capable of accepting moisture.

15. A printing plate in which the ink-receptive image is composed of an unreticulated gelatinethat is capable of accepting moisture.

16. A planographic printing plate in which the ink-receptive image is composed of a colloid that is free from granular structure and capable of accepting moisture.

17'. A planographic printing plate" in which the ink-receptive image 1s composed of a gelatine that is tree from granular structure and capable of accepting moisture.

18. A printing plate capable of printing after mechanical inking and comprising an unreticulated colloidal film that in selectively receptive to ink, all of the original colloidal material of the film being present in the finished plate.

19. A printing plate capable of printing after mechanical inking and comprising an unreticulated gelatine film that is selectively receptive to ink, all of the original gelatinous material of the film being present in the finished plate.

20. A printing plate capable of printing after mechanical inking and comprising an unreticulated colloidal film having the image represented by a mere change in the water-receptivity of the corresponding portions of said film.

21. A printing plate capable of printing after mechanical inking and comprising an unreticulated gelatine film having the image represented by a mere change in the water-receptivity of the corresponding portions of said film.

22. A printing'plate comprising a colloid film having the image represented thereon by means of dots or grains formed in a camera.

23. A printing plate comprising an unreticulated colloid film having the image rep resented thereon by means of dots or grains formed in a camera.

2 1. A printing plate capable of printing after mechanical inking and comprising an unreticulated colloidal film having the image represented by a mere change in the water-receptivity of the corresponding portions of said film and without the removal of any portions of the colloidal material of the film.

25. A printing plate capable of printing after mechanical inking and comprising an unreticulated gelatine film having the image represented by a mere change in the water receptivity ot the corresponding portions of said film and without the removal of any portions of the gelatinous material of the film.

26. A printing plate capable of printing atter mechanical inking and comprising a colloid film, in which has been incor porated a chromic acid salt that has been exposed to light, and the hardness of the lightafiected portions of which has been increased by the application of other hardening-means.

27. A printing plate capable of printing ill) after mechanical inking and comprising a gelatine film, in which has been incorporated a chromic acid salt that has been ex osed to light, and the hardness of the lig t-afi'ected portions of whichhas been increased by the application of other harden ing means. 1

28. A printing plate capableof printing.

after mechanical inking and comprising a colloid film consisting of hardened and relatively unhardened portions, the hardened portions comprising a chromic acid salt, and having been subjected to exposure to light and further subjected to the action of a hardening agency, the relatively unhardened portions remaining relatively unaltered.

29. A printing plate capable of printing after mechanical inking and comprising a gelatine film consisting of hardened and relatively unhardened portions, the hardened portions comprising a chromic acid salt, and having been subjected to exposure to light and further subjected to the action of a hardening agency, the relatively unhardened portions remaining relatively unaltered.

30. A printing plate comprising a colloid film consisting of hardened and relatively unhardened portions, the hardened portions comprising a chromic acid salt and having been subjected to exposure to light and further subjected to the action of alcohol, the relatively unhardened portions remaining relatively unaltered;

31. A printing plate comprising a gelatine film consisting of hardened and relatively unhardened portions, the hardened portions comprising a chromic acid salt and having been subjected to exposure to light and further subjected to the action of grain alcohol, the relatively unhardened portions remaining relatively unaltered.

32. A printing plate comprising a colloid film consisting of hardened and relatively unhardened portions, the hardened portions comprising a chromic acid salt and having been subjected to exposure to light and further subjected to the action of grain alcohol and heating, the relatively unhardened portions remaining relatively unaltered.

A printing plate comprising a gelatine film consisting of hardened and relatively unhardened portions. the hardened portions comprising a chromic acid salt and having been sub ected to exposure to light and further subjected to the action of grain alcohol and heating. the relatively unhardened portions remain ng relatively unaltered.

film in which has been incorporated a chromic acid salt that has been exposed to light and the hardness of the light-afiectcd portions of which has been increased by the use of a hardening agent which, when the excess thereof has been removed, leaves said light-affected portions in a dry state.

35. A printing plate comprising a colloid film in which has been incorporated a chromic acid salt that has been exposed to light and the hardness of the light-affected portions of which has been increased by the use of a hardening agent which, when the excess thereof has been removed, leaves the said film in a dry state.

36. A printing plate comprising a colloid film inwhich has been incorporated a chromic acid salt that has been exposed to light, and the hardness of the light-affected portions of which has been increased by the use of a hardening agent which is not absorbed by the film.

37. A printing plate comprising a colloid film in which has been incorporated a chromic acid salt that has been exposed to light, and the hardness of the light-afl'ected portions of which has been increased by the application of a hardening agent which is not absorbed by said light-aiiected portions.-

38. A printing plate comprising a colloid film in which the parts corresponding to the image are relatively highly receptive to ink when wet with water.

39. A printing plate comprising a gelatine film in which the parts corresponding to the image are relatively highly receptive to ink when wet with water.

40. A printing plate comprising an unreticulated colloid film in which the parts corresponding to the image are receptive to ink when wet with water.

41. A printing plate comprising an unreticulated gelatine film in which the parts corresponding to the image are receptive to in-k' w'hen wet with water.

42. A printing plate comprising a colloid film having parts. corresponding to an image that are receptive to ink, the other portions of said film being capable of continuously repelling ink by the mere application of water.

' 43. A printing plate comprising a gelatine film havlng parts corresponding to an image that are receptive to ink, the other portions of said film being capable of continuously repelling ink by the mere application of water.

44. The process of making a printing plate, comprising sensitizing a colloid film with a chromic acid salt, subjecting the same to the selective action of light to form an image, hardening the light-affected areas more than the unaffected areas, and removing the unaffected chromic acid salt. 34. A printing plate comprising a colloid 45. The process of making a printing plate, comprising sensitizing a colloid film with a chromic acid salt, subjecting the same to the selective action of light to form an image, and hardening the light-affected neonate areas more than the unafiected areas without removing any portion of the colloid. V

lb. The process of making a printing plate, comprising sensitizing a colloid film with a chromic acid salt, subjecting the same to the selective action. of light to form an image, hardening the light-affected areas,

removing the unaffected chromic acid salt, and heating the plate.

47. The process of making a printing plate, comprising sensitizing a colloid film with achromic acid salt, subjecting the same to the selective action of light to form an image, hardening the light-affected areas without removing any portion of the colloid, and heating the plate.

A8. The process of making a printing plate comp-rising sensitizing a gelatine film with a chromic acid salt, subjecting the same to the selective act-ion of light'to form an image, hardening the light-affected areas more than the unaffected areas, and removing the unafiected chromic acid salt.

A9. The process of making a printing plate comprising sensitizing a gelatine film with a chromic acid salt, subjecting the same to the selective action of light to form an image, and further hardening the light affected areas more than the unall'ected areas without removing any portion of the gelatine. c

50. The process of making a printing plate comprising sensitizing a gelatine film with a chromic acid salt, subjecting the same to the selective action of light to form an image, further hardening the light-ail'ected areas, removing the unafii'ected chromic acid salt, and heating the plate.

51. The process of making a printing plate comprising sensitizing a gelatine film with a chromic acid salt, subjecting the same to the selective action of light to form an image, 'lurther hardening the lightaffected areas without removin any portion of the gelatine, and heating the plate.

52. The process or makin a printing plate comprising forming a. colloid film on the plate and sensitizing the film with a chromic acid salt by applying thereto a solution of said salt, exposing said film to a light image and hardening said film.

53. The process of making a printing plate comprising forming on a backing a colloid film that is sensitized by a chromic acid salt and drying said film by a temperature that is not greater than 130 F, exposing said film to a light image and hardening said film.

5d. The process of making a. printing plate comprising forming a gelat-ine film on the plate and sensitizing the film with a chromic acid salt by applying thereto a solution of said salt, exposing said film to a light image and hardening said film.

55. The process of making a printing plate that is' not greater than 130 comprising lormin on a backing a gelatine film rendered sensitive by a chromic acid salt and drying said film by a temperature F, exposing said film to a light image and hardening said film.

56. As a composition of matter, a colloid in which has been incorporated a chromic acid salt, which has been hardened by the action of light, and the hardness of which has been increased by immersion in grain alcohol.

57. As a composition of matter, a colloid,

in which has been incorporated a chromic acid salt, which has been hardened by the 59. As a composition of matter, a colloid,

in which has been incorporated a chromic acid salt and which has been hardened by light, and the hardness of which has been further increased by the application of grain alcohol as a hardening agent.

- 60. As a composition of matter, a gelatine in which has been incorporated a chromic acid salt, which has been hardened by the action or light, and the hardness of which has been increased/by immersion in grain alcohol.

61. As a compositlon of matter, a gelatine in which has been incorporated a chromic,

acid salt, which has been hardened by the action of light, and the hardness of which has been increased by immersion in grain alcohol and by heating.

62. As a composition of matter, a, gelatine, in which has been incorporated a chromic acid saltand which has been harddened by light, and the hardness oil which has been further increased by the application of a hardening agent.

63. As a composition of matter, a gelatine, in which has been incorporated a chromic acid salt, and which has been hardened by light and the hardness of which has been further increased by the application of a grain alcohol as hardening agent.

64. As a composition of mattena colloid, in which has been'incorporated a chromic acid salt some only of which has been hardened by light, and the hardness of which has been further increased by heating both the hardened and unhardened portions of said colloid being present in said composition.

65. As a composition of matter, a gela- .tine,- in which has been incorporated av been hardened by light, and the hardnessof which has been further increased by heating both the hardened and unhard'ened porplication of a hardening agent and by heating it.

68. In the process of forming a printing plate having a colloid film, the step which comprises hardening the film with formaldehyde before sensitizing it. v

69. In the process of forming a printin plate having a colloid film, the step 0 hardening the film before sensitizing it.

70. In the process of forming a printing plate having a gelatine film, the step of hardening the film before sensitizing it.

71. In the process of forming a printing plate having a colloid film, thestep which comprises hardening the film with grain alcohol and formaldehyde before sensitizing it. V

72. In the process of forming a printin plate having a gelatine film, the step which comprises hardening the film with grain alcohol and formaldehyde before sensitiz- 73. The process of making a printing plate comprising coating a backing with gelatine, hardemng the gelatine with formaldehyde, sensitizing the gelatine with a chromic acid salt, hardening the light-affected areas by the use of means which will not equally harden the unaffected areas, and

. then removing the unaffected chromic acid salt from the plate.

74. The process of making a printing platecomprising coating abacking with colloid, hardening the'colloid with formaldehyde, sensitizing -the colloid with a chromic acid salt, hardening the light-affected areas by the use of means which will not equally harden the unaffected areas,'and

then removing the unaffected chromic acid salt from the plate. r

75. The process of makin a printing plate comprising coating a backing with gelatine, hardening the gelatine with formal: dehyde, sensitizing the gelatine with a chromic acid salt, applying a light-restraining agent thereto, hardening the light-affected areas by the use of means which will not equally harden the unaffected areas-and thenremoving the unaffected chromic acid salt from the plate.

76. The process of making a printing plate comprising coating a backing with a colloid, hardening the colloid with formaldehyde, sensitizing the colloid with a chromic acid salt, applying a light-restraining agent thereto, hardening the light-affected areas by the use of means which will not equally harden the unaffected areas and then removing th unaffected chromic acid salt from the plate.

77. The process of making a printin plate comprising coating a backing witfi gelatine, hardening the gelatine with formaldehyde, sensitizing the gelatine with chromic acid salt, hardening the light-ab 'fected areas by the use of means which will not equall harden the unaffected areas, removing t e unaffected chromic acid salt from the plate and then heating said plate.

78. The process of making a printing plate comprising coating a backing with a colloid, hardening the colloid with formaldehyde, sensitizing the colloid with a chromic acid salt, hardening the light-affected areas by the use of means which will not equally harden the unaffected areas, re-

moving. the unaffected chromic acid salt from the plate and then heating said plate.

79. The process of makin aprinting plate comprising coating a backing with gelatine. hardening the gelatine with formaldehyde. sensitizing the gelatine with a chromic acid salt, applying a light-restraining agent thereto, hardening the light-affected areas by the use of means which will not equally harden the unaffected areas, removing the unaffected chromic acid salt from the plate, and then heating said plate.

80. In the process of forming a printing plate having a colloid film, the step which comprises increasing the difference in waterreceptivity' between those portions of the plate which are more receptlve to water than those which are less so.

81. In the process offorming a printing plate having a colloid film, the step which comprises increasing with grain alcohol the difference in water-receptivity between those portions of the plate which are more receptive to water thanthose which are less so.

82. The process of printing which comprises the application of ink to a wet unreticulated colloidal surface and the printing or transfer of said ink.

83. The process of printing which comprises giving to portions of an unreticulated colloidal surface the capacity when wet to receive ink to form an image, and to other portions of said surface the capacity to repel ink. applying ink to said surface and printing therefrom.

84. The process of printing Which comlll ' All till iataata prises the application of ink to a wet unreticulated colloidal surface, the transfer of said ink to a rubber blanket, and the trans fer of said ink image from said rubber blanket to its final support.

85. The process of printing which com- I prises forming on a backing a colloid coating, sensitizing said colloid with a chromic acid salt, exposing said colloid to a light image, accentuating the difierence in waterreceptiveness between the exposed and unexposed portions of the colloid, moistening said plate and applying ink thereto.

86. The process of printing which comprises forming on a backing a colloid coating, sensitizing said colloid with a chromicacid salt, exposing said colloid to a light image, accentuating the difference in waterreceptiveness between the exposed and unexposed portions of the colloid by hardening said exposed portions, moistening said plate and applying ink thereto.

87. The process of printing which comprises forming on a backing a gelatine coating sensitizing said gelatine with a chromicacld salt, exposing said gelatine to a light image, accentuating the difi'erence in waterreceptiveness between the exposed and unexposed port-ions of the gelatine by hardening said exposed portions, moistening said plate and applying greasy ink to the less water-receptive areas.

88. The process of printing which c0mprises formlng on a backing a gelatine coating, sensitizing said gelatine with a chromic acid salt, exposing said gelatine to a light image, accentuating the difierence in waterreceptiveness between the exposed and unexposed portions of the gelatine, moistening said plate and applying ink thereto.

89. The process of printing which comprises forrning on a backing a gelatine coating, sensitizing said gelatine with a chromic acid salt, exposing said gelatine to a light image, accentuating the difierence in waterreceptiveness between the exposed and unexposed portions of the g'elatine, moistcning said plate and applying ink thereto.

90. The process of printing comprising forming a plate having a colloid film, renvdering said film selectively water receptive according to the image desired, applying only a single ink-repelling medium to said plate and then applying ink to said plate.

91. The process of printing comprising forming a plate having a colloid film, rendering said film selectively watcr-receptive according to the image desired, applying only water to saidplate and then applying ink to said plate.

92. The process of printing which comprises applying ink to a wet surface, emulsifying said ink with water from said wet surface, and printing said ink.

93. The process of printing which com.- prises applying ink to a wet colloid surface, emulsifying said ink with water from said wet colloid surface, and printing said ink.

94. The process of printing which cornprises applying ink. to a wet gelatine surface, emulsifying said inkwith water from said wet surface, and printing said ink.

95. The process of printing which comprises applying ink to a wet surface, emulsifying said ink with water from said wet surface, depositing saidemulsified ink upon a rubber blanket, and redepositing said emulslfiedink upon the print or final support.

96. The process of printing which comprises applying ink to a wet colloid surface, emulsifying said ink with water from said wet surface, depositing said emulsified ink upon a rubber blanket, and redepositing said emulsified ink upon the print or final support. I

97. The process of printing which comprises applying ink to a wet gelatine surface, emulsifying said ink with water from said wet gelatine surface, depositing said emulsified ink upon a rubber blanket, and redepositing said emulsified ink upon the print or final support. 7

98. The process of printing which cornprises the steps of applying ink to an unretit-ulated colloidal planographic plate, the image on which has been formed by the action of light and which has remained melit chanically unmodified between the step of exposure to light and the said step of applying the ink, and impressing said ink upon a support.

99. The process of making a printing plate comprising forming on a backing a colloid coating, rendered sensitive with a chromic acid salt, exposing the same to a light image, hardening the light-affected areas by means which will not equally harden the unaffected areas, removing the unaffected chromic acid salt from the plate, and heating the plate, and during which process avoiding heating the plate to 130 F. while unaltered chromic acid salt is present in the colloid coating.

100. The process of making a printing plate comprising forming on a backing a gelatine coating rendered sensitive with a chromic acid salt, exposingthe same to a light image, hardening the light-effected areas by means which will not equally harden the unaffected areas. removing the unaffected chromic acid salt from the plate, and heating the plate, and during such process avoiding heating the plate to F. while unaltered chromic said gelatine to a light image, then without removing the unaltered portion of said salt, accentuating the difference in water-receptiveness between the exposed and unxposed portions of the gelatine, removingthe unafected portions of said salt from the said latin'e coating hardening said gelatine coatmg and heating said plate, moistening said plate, applying ink thereto, emulsifying said ink with the said water on said plate and transferring said ink. s

102. The process of printing which comprises forming on a backing a colloid coat 1n hardening said coating, sensitizing'said co loid with a chromic acid salt, exposing said colloid to a light image, then without removing the unaltered portion of said salt, accentuating the difference in water-receptiveness between the exposed and unexposed portions of the colloid, removing the unaffected portions of said salt from the said colloid coating, hardening said colloid coating and heating said plate, moistening said plate, applying ink thereto, emulsifying said ROBERT-JOHN.