US1300729A - Process of preparing grained-tone photographic negatives and positives and producing printing-plates therefrom. - Google Patents

Description

W. C. HIJEBNER. PROCESS OF PREPARING GRAINED TD NE PHOTOGRAPHIC NEGATIVES AND POSITIVES' AND PRODUCING PRINTING PLATES THEREFROM.

APPLICATION FILED MAR-171 IQIB. 1,390,729., Patented Apr. 15, 191$).

/l TTOR/VEYi n onto WILLIAM C. HUEBNER, OF BUFFALO, NEW YORK, ASSIGNOR TO HUEBNER-BLEISTEHT PATENTS (30., OF BUFFALO,

NEW 'YORK.

PROCESS OF PREPARING GRAINED-TONE PHOTOGRAPHIC NE GATI VES AND POSITIV ES AND PRODUCING PRINTINGrPLATES THEREFROM.

Specification of Letters Patent.

Patented Apr. 15, 1919.

Application filed March 17, 1916. Serial No. 84,880.

To all whom it may concern Be it known that I, WILLIAM C. HUEBNER, a citizen of the United States, residing at Bufialo, in the county of Erie and State of New York, have invented a new and useful Improvement in Processes of Preparing Grained-Tone Photographic Negatives and Positives and Producing Printing-Plates Therefrom', of which the following is a specification.

This invention relates to a method for producing monotone or Nos. 954,291 and 954,292, both dated Jan. 23,

1912; 1.043.430, dated Nov. 5, 1912, and 1,201,048, dated Oct. 10, 1916, granted to W. C. Huebner. assignor to Huebner, Bleistein Patents Co., and also for preparing the negatives and positives used in making the press plates. 7

The photographic negatives or positives used in such machines should be of a more perfect and finished quality than heretofore attained by the ruled or grained screen methods, because the metal printing plates produced in these photo-composing machines are not adapted for local tone correction, as this would not be economical since the printing plate often carries the same subject repeated many times, and aside from the large amount of work involved, it is not possible to correct several repeats upon the printing plate exactly alike. practical and commercial production that the image formed upon the printing plate by the photographic negative or positive used in these machines must carry-the required tones to reproduce the copy in a satisfactory manner.

In photo-mechanical reproduction methods where either half-tone ruled or grained screens are used for producing negatives and positives for making monotone or polychrome printing plates, it is found that the full tone values of the copy are not reproduced exactly, since the parts of the copy which are white. and the parts which are black. will carry a fine dot or grain in the negative. Also. that the light tones next to the whites will be darker, and the deep polychrome press printing plates of the kind which are made I for example by photo-composing machines It is lmperative for tones next to the blacks will be lighter, due to the use of these screens for producing printing units on the negative and positive, in order to adapt them for the successful production of photo-mechanical printing plates. The manipulation by timing and flashing through lens diaphragms or various shapes and sizes of stops, during exposure through the screens does not compensate for the loss of tone gradation, and the resulting image on theprinting plate made from such screened negatives or positives is fiat or gray in appearance when compared to the copy from which the negative or positive was made. a

Such defects are remedied by reetching, burnishing. overlaying, and underlaying the printing plates when the plates are made from relief printing. But when the negatives or positives are made for pianographic printing, these tone defects must be corrected on either the negative, the positive or on the photo-printed planographic stone or plate. This is a time-consuming operation and has been found in practice to seriously delay the execution of orders, on account of the extra labor of correcting the light anddark tones on the negatives.

The negatives made through ruled or grained screens cannot give satisfactory results unless they are'tone corrected by hand, to eliminate the false tones rendered by the use of the screens, and this hand operation requires much experience, skill and good judgment in manipulating the tones and is a costly and time consuming operation.

It is the object of this invention to overcome these defects and meet the specific requirements and conditions created by the use 'of photo-composing machines by providing a In said draw;

ing Figure 1 shows in section a plate or film A provided with a light-sensitive grainproducing coating. Fig. 2 shows in section the plate shown in Fig. 1, in position beneath a tone corrected negatve or positive plate B ready for exposure to light. Fi 3' is a face view of the printing plate A after is has been exposed to light and developed- Fig. 4:

tone values, and that if this tone corrected negative or positive is placed face down in contact with'a suitable light-sensitive grainproducing coating on a transparent or semitransparent plate A and exposed to light, the image can be developed and broken up into opaque and transparent, or semi-transparent grains, which carry a far greater tone range from black to clear white, and give a more faithful reproduction of all interurediate tones of the positive than can be secured by the use of screens.

The function ofthe opaque grains so produced is to block the passage of light, and the function of the transparent or semitransparent grains is to permit the passage of lightv to act upon a sensitized printing 7 plate, and this light action forms the image either in positive or negative as desired, upon the printing plate. The result is that w1th very little hand work, a highly satisfactory print is produced directly upon the metal printing plate, also that when exposed and repeated in the photo-composing machine hereinbefore referred to, this print on the metal printing plate yields a finer quality of work and longer editions from the plates than can be attained by other methods of grain printing. Many duplicate or re peat exposures can be made through this grained tone negative or positive upon a suitably sensitized metal plate and the ne ative or positive can be stored away for uture use.

A subject in colors can be reproduced 'by this process as follows:

A photogra hic negative of the subject is made prefera ly on grained glass, a violet color filter being used or the subject being illuminated with violet light, according to the method used. During exposure the yellow color of the copy is separatedfrom the other colors and a record negative of the yellow color isinade. I

Record negatives of the red and blue These positives B, when dry, are tonecorrected by hand. The tones can be darkened by application of suitable mediums, such as fine graphite powders or pastes, the fine tooth of the grained glass plate providing a ready hold for these mediums, and

the' tones can be lightened or entirely removed by the use of some suitable medium, such as powders of cuttlebone, or pumice, or other gritty substance.

After correcting errors in tones of defective color separations, or makin other desired changes, the positive B is la1d face down upon a plate A (preferably slightly grained) of glass or other suitable transparent 0r semi-transparent material, having a light-sensitive grain-producing coating. A coating solution 'of gelatin, potassium bichromate, ammonium bichromate, calcium chlorid, ether, alcohol and water is suitable for this purpose. The positive B is exposed to light with its face in contact with this sensitized surface, a piece of black felt being preferably placed at the back of the sensitized plate to avoid halation. Instead of first making a negative and then making a positive from this and tone-correcting the positive, it is possible to make the negative in grained glass and tone-correct this plate and use it instead of the positive for printing on the light-sensitive grain-produclng.

surface.

After exposure, the sensitized late A is developed. If the above specified sensitive coating is used the plate is developed in water until all of the bichromate is washed .out and the plate is then allowed to dry.

The ortions of the gelatin acted upon by the light do not absorb moisture but the parts not affected by light do absorb mois-- ture and swell accordingly. These moist parts will repel greasy ink or the likewhile theparts affected by light will repel moisture and accept greasy ink or analogous opaque substance which can be applied by a sutable composition roller C or in other ways. If it is desired to render the grain carrying the opaque ink or matter more dense. the surface can be dusted with defiocculated graphite, lampblack or other powder D which will adhere to the link.

When the ink has been treated thus,'the image will be represented thereon by opaque and transparent or semi-transparent. grains and the plate can be used as a photographic negative. This plate which carries the grained tone image, after being dried and beplaced in a also preferably varnished to preserve-it, can photo-composing machine,

. such as mentioned, together with a sensias required'to and repeat exposures on the "press plate.

the transparent or v the opaque grains can be cleaned oif the will adhere to the desired with with fin The passage of light isblocked by the opaque grams but the light passes through semi-transparent grains and acts upon the sensitive surface of'the press plate. After suitable development, the

image or images in grained tone gradations is or are produced upon the press plate. from which many thousand impressions can be taken in a suitable press. Thisgrained tone negative or positive A on glass can be used indefinitely for the-production of printmg plates. It can be stored away and used whenever convenient as it'does notdeterioratefby use, since it only passes light tot'hesensltized press plate during exposure. For producing monotone printing plates it is of course only necessary to make and correct one photographic positive of the copy, and makeone grained tone negative therefrom, the same being made in the man ner explained.

It isnot intended to .limit this invention to the particular formula above described for the light sensitive grain producing solut on, as other ingredients can be used provided they are prepared so as to maintain a proper balance of opaque and transparent units to produce proper tone gradations. Opaque matter can also be applied to this gralned surface in ways other than above described. as for instance by flowing with suitable chemicals or. opaque solutions which parts. and dusting these parts with suitable powders, thus pro ducing opaque, transparent and semi-transparent grains which will make up a screenless grained tone negative suitable for photographic printing upon the sensitized surfaces of printing plates or cylinders. The plate or film could also be rolled up a transparent greasy material on the light ardened'portions and an opaque nonin which case this only to the repelled by Another the plate either of opaque or semi-transparent nature,

as for instance tacky varnish, and dusting e opaque powder, such as graphite, lampblack, or fine bronze powders, after setting, or loose particles of powder lying between plate by an air blast or by brushing carefully with a soft brush or other suitable means.

Instead of glass plates, transparent or greasy solutihn flowed over the entire plate combining and drying the surplus.

'semi-transparent films of celluloid or the like'can be used as a base for carrying the "grain producing solution,

so these can be applied to either flat metal printing plates or'to-curved metal surfaces such as intaglio printing cylinders.

claim as my invention 1. A process of preparing, without the use of screens, grained tone negatives and positives, consisting in providing a transparent or semi-transparent plate or film with a lightsensitive grain producing coatmg, exposing the same to light under a suitable image and developing the same, thereby producing a surface having grains which -will receive and grains which will repel a parent or semi-transparent plate or 'film.

with a light sensitive grain producing coating, exposing the same to light under a suitable image and developing the same. thereby producing a surface having grains which will receive and grains which will repel a greasy opaque material, and then applying the greasy opaque material to the surface to provide opaque and transparent or semitransparent grains which make up the image and are adapted respectively to block and permit the passage of light for acting upon a sensitized printing surface.

3. A process of preparing without the use of screens, grained toned negatives and positives, consisting in making a photographic negative or positive ofa subject on transparent or semi-transparent material, and

tone correcting said negative or positive,

providing a transparent or semi-transparent plate or film with a light sensitive grain producing coating, exposing the same to light under said corrected positive and developing the same, thereby producing a surface having grains whichwill receive and grains which will repel a coating material, and then applying opaque material to said same thereby producing a surface having light hardened grains and moisture swelled grains which Will repel a coating material, and then applying opaque material to said surface to provide opaque and transparent or semi-transparent grains Which make up the image and are adapted respectively to block and permit the passage of light for acting upon a sensitized printing surface.

5. A process of producing press printing surfaces, consisting in preparing, Without the use of screens, a grained tone negative or positive, by providing a transparent or semi-transparent plate or film with a light sensitive grain producing coating, exposing the same to light under a suitable image and developing the same, thereby producing a surface having grains Which will receive and grams whlch W111 repel a coating material, then applying opaque material to said surface to provide opaque and transparent or semi-transparent grains which make up the image and are adapted respectively to block, and permit the passage of, and then WILLIAM C. HUEBNER.

Witnesses: C. W. PARKER, A; L. MCGEE.

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