US1944354A - Photogravure process and metal plate therefor - Google Patents

Description

1934- N. LUDVIGSENI 5 PHOTOGRAVURE PROCESS AND METAL PLATE THEREFOR Original Filed Dec. 16, 1929 EL; Luay g;; y

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Patented Jan. 23, 1934 UNITED STATES PHOTOGRAVURE PROCESS AND METAL PLATE THEREFOR Niels Ludvigsen, Paris, France Application December 16, 1929, Serial No. 414,437y and in France December .9, 1928. Renewed October 25, 1933 12 Claims. (Cl. 95 5.7)

The object of the present invention is to simplify the preparation of photogravure processes as hitherto efiected.

The main object of the invention isto-avoid the multiple manipulations with dangerous ingredientssuch as collodion, nitrate of silver required in'photogravure processes hitherto and in consequence to reduce to a minimum expensive material and experienced personnel.

The present invention relates firstly to a photogravure process the feature of which is that a grain is formed on a metal 'plate by impression for example, then after the plate hasbeen sensitized, the image to be reproduced is formed thereon, the printing plate then being finished by the known means of washing, heating and etching.

According to a modification of the invention, an initial grain corresponding to the clear portions of the image is first formed on the metal plate, then the plate is coated with a coating of sensitive gelatine and on this coating a second grain is formed corresponding to the black and tion, such as gelatine or albumin treated with bichromate of ammonia. Finally, a second grain corresponding to the half tones isformed by impression on the sensitive coating.

On the thus prepared metal plate, is then applied a glass plate bearing an image taken in an ordinary photographic apparatus and which is to be reproduced by photogravure.

The operation is exactly as if a proof is to be taken on paper, the metal plate replacing such paper.

The areas of the sensitive film corresponding to the areas of the glass plate traversed by the light become hardened, whereas the other areas of such film not reached by th'elight remain water-soluble.

In consequence, when the plate is washed with I water, the sensitive film goes away in the areas thus leaving bare the initial grain impressed directly on the metal.

On the contrary the areas of the sensitive film hardened by the action of the light are not removed by the washing with water, such areas corresponding with the blacks and half-tones of the image.

' By heating, the still remaining sensitive film is definitely fixed. Finally, the plate is etched by any suitable known method.

The invention extends to the above described processes whatever be the arrangements selected for carrying them into efiect. Moreover, the invention extends also, as a new product, to metal plates enabling these processes to be carried out in a particularly certain and convenient manner.

These metal plates have the features set forth in the following description and specified in the claims annexed to the end of such description.

Metal plates according to the invention are illustrated by way of example on the accompanying drawing, in which:-

Fig. 1 is a diagrammatic section of a metal plate. a

Fig. 2 is an elevation of a metal plate showing the image to be reproduced.

Fig. ,'3 is a diagrammatic section of a metal plate accordingto a modification of the invention.

The metal plate illustrated diagrammatically in section in Fig. 1 is a zinc plate 10 having an 35 initial reticulation or stippling 11 obtained by impression, for example, then a sensitive film 12R and finally a second grain 13.

The plate has not yet received the projectio of the image.

Assuming that it is desired to reproduce the image of a ship, the zinc plate 10 will present clear zones 15 forming the background of the image, black zones 16 corresponding-to the superstructure of the ship and half-tone zones 1'? corresponding for example to the hull of the ship. The zinc plate 10 then bears an initial grain corresponding to the clear zones of the image, such initial grain 11 being covered with a sensitive 'film' 12, on which there is a second grain 13 4 corresponding to the dark zones 16 or to the half -tone zones 17. I

The plates to which the invention extends may obviously be very differently constituted, for example:

For a contrasted image the grain 13 of the halftones 17 is weak; for-a nebulous image on the contrary the grain of the clear portions 15 is weak.

This predominance can be carried almost to no the point of disappearance of one of the grains, particularly in the case of the formation of printing surfaces without half-tones or without clear portions. In the etching of such plates the initial grain 11 and the second grain 13 will work under very different conditions.

The points of the first grain 11 imposed before the sensitizing are independent of the sensitive film 12. Although it happens thereon, they will fulfil their mission of resisting the acid during etching and later of preventing the inking rollers from penetrating into the clear parts of the image at the time of printing.

The second grain 13 imposed on the sensitive film 12, has, on the contrary, only a photo-chemical action. It disappears when after insulation the image is developed. The sensitive film remains there and it receives the light and will resist the attack of the acid during etching.

These plates are commercial articles which can be sold to newspapers, especially provincial newspapers.

I-claim:

1. The method of producing photogravure printing surfaces, which consists in providing an acid resisting grain upon the smooth face of a metal plate, said grain having uniform dots regularly disposed, thereafter coating the grained surface with a light sensitive substance, providing a grain on said sensitive surface, said second grain having uniform dots regularly disposed, photographing, developing and etching the plate substantially as described.

2. The method of producing photogravure printing surfaces, as claimed in claim 1, in which the individual points of the second graining are disposed intermediate the points of the first graining, substantially as described.

3. A photogravure process for relief printing .with metal plates which consists in forming an acid resisting grain on a smooth uncovered metal plate, this grain having uniform points, regularly disposed, thereafter sensitizing the plate thus prepared, then exposing washing, heating and etching the cliche in the usual way.

4. A photogravure process for relief printing with metal plates which consists in forming an acid resisting grain on a smooth uncovered metal plate, then coating the plate with a sensitive substance, forming a grain on said sensitive layer above the clear portions of the said first grain, bringing thereafter by photographic exposure upon the plate so prepared the picture to be reproduced, developing the plate and etching the plate by means of an acid.

5. The method of producing photogravure surfaces, which consists in providing an acid resisting grain upon the smooth face of a metal plate, said grain consisting of uniform marks regularly disposed, thereafter coating the grained surface with a light sensitive substance, providing a grain on said sensitive surface, said second grain consisting of uniform opaque marks regularly disposed, thereafter photographically exposing, developing and etching the plate substantially as described.

6. A method as claimed in claim 5 in which the individual marks of the second graining are disposed intermediate the marks of the first graining.

7. A process as claimed in claim 3, in which said grain is formed by printing on the plate with insulating ink.

8. As an article of manufacture a metal plate, said metal plate having a smooth surface provided with a plurality of marks of acid resisting nature and having superimposed thereon a light sensitive layer and further, a plurality of opaque marks provided on said sensitive layer. I

9. As an article of manufacture, a metal plate having a smooth surface provided with an acid resisting grain of uniform dots regularly disposed, and a light sensitive layer superimposed thereon, and a second grain of uniform opaque dots regularly disposed and arranged on said sensitive layer.

10. A metal plate as claimed in claim 9 in which the dots of the second graining are disposed intermediate the dots of the first graining.

11. As an article of manufacture, a photogravure printing plate having a printing surface permanently smooth and uninterrupted throughout its extent, an acid resistant grain superimposed directly on said surface and a light sensitive layer superimposed on said grain.

12. As an article of manufacture, a photogravure printing plate having a printing surface permanently smooth and uninterrupted throughout its extent, printed impressions of acid resistant material superimposed directly on said surface and forming a grain thereon and a light sensitive layer superimposed on said grain.

NIELS LUDVIGSEN.

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