US1517296A - Aet of printing - Google Patents

Description

Dec. 2, 1924.

E. A. KUNZ ART OF PRINTING Filed Feb. I, 1922 Patented Dec. 2, 1924.

UNITED STATES EDWARD A. KUNZ, OF VIILMETTE, ILLINOIS.

ART OF PRINTING.

Application fried February 1, 1922.

To all 107mm it may concern:

Be it known that I, EDWARD A. KUNZ, a citizen of the United States, residing at Wilmette, in the county of (look and State of Illinois, have invented certain new and useful Improvements in the Art of Printing, of which the following is a specification.

My invention relates to the art of printing and refers particularly to a new form of matrix and the process of making same by means of which greatly superior results are obtained in the printing process.

It is well known that in printing either black or color where either flat bed or rotary printing presses are used, much time is consumed by the operators because they have to resort to certain manipulations of the plate and press, technically known as making ready, which consists of so-called underlaying the plate and overlaying the impression cylinder. In order to provide an extended life for a half tone printing plate, it has been common practice to provide an underlay or overlay commonly known as make ready for the purpose of providing a relatively heavy pressure in the press on the heavy tones, less pressure on the intermediate tones and even less pressure on the lighter tones. This procedure increases the life of a printing plate very materially. The make ready referred to is, at best, however, very crude, very expensive and relatively short lived. A ccording to the present invention, the make ready may be dispensed with, or the article forming part of the subject matter of the present invention may be used as a decidedly improved make ready.

According to the present invention, a matrix is provided for application to the face of a printing plate, prior to the printing operation said application being made under pressure when. said plate is put into a relatively soft condition, whereby the levels on the half tone dots or projections of said plate are varied according to their tones. The term matrix is to be distinguished from the printing plate, make ready. overlay or underlay. he matrix according to the present invention is intended to be squeezed into a printing plate to vary the levels of the printing dots of said plate in accordance with the tone values of saiddots. An object of my in- Serial No. 533,154.

vention is to provide an improved matrix and method of making same for accomplishing the above purpose.

A further object is to reduce the cost and time required for the printing operation.

A further object is to improve the quality of the half tone printing particularly where true tone and intricate delineation are required.

A further object is to provide an improved matrix and method of making same which will prolong the life of a printing plate.

Although my invention has a wide field of application it is particularly useful in half-tone printing from original plates or electrotypes especially in multi-color printing where great accuracy is required and where it is highly desirable that the great amount of time for the make-ready operation should be cut down to the minimum and that after the form or printing plates are properly imposed and registered it should be possible to start to print in a much shorter time than heretofore and to print the greatest possible number of clear impressions before the printing plates show the effect of wear.

I accomplish the results set forth by means of making a matrix, having the design reproduced on a sheet of metal or on a sheet of especially prepared paper and so treating the matrix that different portions of the design are brought to different levels with respect to the main surface of the matrix; that is, the portions of the design which are to print with a light impression, and the portions that are to print with darker impressions, will be so treated that when completed I will have an exceed ingly accurate matrix with the surface of the design at different levels according to the lightness or darkness of the impression to be finally printed for the different portions of the design. Such a matrix may housed for a variety of purposes. I

It has heretofore been customary in ma king the so-called overlay or underlay, to build up the surface which supports the paper or the plate to be printed so that this surface is at difl'erent levels, the higher levels being designed to force the paper with greater pressure into contact with the print ing plate at the portionswhich it is desired shall be printed heaviest, while at the same Jil time the portions of the design having the intermediate tones and high lights in the finished printed impression are subjected to correspondingly lighter pressure. This result is ordinarily obtained by making an overlay or underlay in which pieces of paper are pasted one over the other until the desired configuration is obtained. It will be noted that not only is this an exceedingly time consuming operation, but in the case of an intricate design it is impossible to construct an overlay or underlay which will vary the pressure as between the parts to be printed heavier and the parts to be printed lighter except in a very crude manner.

I am also aware that in order to increase the life of a printing plate, it has been proposed to build up a matrix with pieces of paper in a similar manner as heretofore described and then subject the printing plate to the action of this matrix by means of pressure so that certain portions of the printing plate are forced to a different level from other portions of the plate, the object being to have the high lights at a somewhat lower level than the portions of the plate which are to print heavier. This operation also is a very crude one on account of the impossibility of constructing a matrix in this manner which will accurately follow all the configurations of the design of the plate.

By the use of my improved matrix I not only avoid the great labor which is entailed in the construction of matrices according to the former systems, but I also make the nriatrix much more accurate so that by its use in the treatment of the printing plate itself, much improved result-s are obtained, and if it should be desired to use my improved matrix as an underlay or overlay (changing from negative to positive) much improved results over former overlays or underlays will be had.

My invention contemplates the imposing on a metal sheet of a half tone design corresponding to the half tone design of the printing plate with which it is to cooperate. The half tone design may be imposed on said metal sheet by any preferred method, this matter of .imposing the design on the sheet metal being only preparatory to the steps instituting my invention. I will now proceed to describe a photographic method. of imposing said design on said metal sheet.

A photographic process by which my matrix is constructed, applied particularly to half-tone relief printing, is to photographically print the design on a metallic matrix plate provided with a sensitized film according to the usual and well known system of making the printing plate. According to the uses to which the matrix is to be applied, it may be printed directly from the original halftone photographic negativefrom which the printing plate is made or a second half-tone photographic plate or film may be made which may be a negative or a positive, and the matrix may be printed from such second photographic plate or film.

The design which is on the face of the printing plate may also be photographed either in a positive or a negative, reverse or otherwise, and the matrix printed therefrom. The matrix may alsobemade by printing the design shown on the printing plate directly onto a special paper or other suitable material and treating such paper or material in a manner similar to that hereinafter described.

The matrix may be constructed of relatively thin sheet metal, such as copper or a suitable alloy thereof, or zinc or suitable alloy thereof, which may be suitably etched with acids or the like, according to the well known system. After the photographic impression has been printed on the matrix the matrix is developed and fixed and etched according to the usual system, the fixed photographic film still remaining on the surface of the matrix. As is well known, in the case of a half-tone plate which is made by a similar system, the high lights differ from the other portions of the plate by the fact that the small dots made by the half-tone screen are much smaller after the etching operation has been performed than the dots which form the heavy or intermediate portions of the design, but the surface of all dots, that is, the high lights or shadows as well as the other intermediate tones or values of the plate, are all in the same plane.

The operation performed on the matrix as described up to this point is substantially the same as is performed on a printing plate according to the well known system. The next step in the treatment of the matrix is to entirely remove the film on the surface and to then again etch the surface of the matrix. The result of this second etching to cause the entire surface of the matrix plate to be affected by the etching fluid. If the matrix is a positive, the highlights of the design will contain. very small half-tone dots, the intermediate tones will contain medium size dots, and shadows or dark portions will contain large size dots or may be entirely solid. 'lhesc dots of various sizes will. be affected by the second etching in different proportions and in such a manner that the tops of the small dots are i'naterially lowered; the medium size dots forming the middle tones will be only partly eaten away, and. the shadows or darkest tones, that is, the portions of the matrix containing the largest dots or solid surface will hardly be affected at all. On the other hand, if the matrix is a negative, exactly the opposite condilll) lit!) lion would result. After this second etching has progressed for a proper period, the matrix is removed from the etching bath and suitably washed to stop further etching.

In order to more clearly understand my invention, reference may be made to the accompanying drawings, in which- Figure 1 represents a vertical section through a half-tone printing plate, on a greatly magnified scale;

Figure 2 represents a similar vertical section through a matrix after the first etch ing, this matrix being made positive with reference to the printing plate shown in Figure 1; and

Figure 3 represents the matrix shown in Figure 2 after the second etching, the condition of the plate after the first etching being shown in dotted lines.

As shown clearly in Figure 1, the printing plate 10 has a surface consisting of a plurality of dots having their tops all in the same plane, but these dots are of different areas, according to the character of printing impression to be made in different parts of the design. For example, the very small (lots 11, 11 represent what will be high lights in the finished printed impression, whereas the larger dots 12, 12 represent in termediate tones, and the very large dots 13, 13 and the solid portion 14 represent the dark tones and heavy shadows.

Similarly in Figure 2, representing the matrix 15 made positive with respect to the printing plate, the small dots 11 11 represent high lights, the larger dots 12, 12 represent intermediate tones, and the very large dots 13 13 and the solid portion 14 represent the dark tones and heavy shadows.

During the first etching of the matrix 15, the sensitive fixed surface coating is allowed to remain on the matrix, so that the surface of all the dots, irrespective of their size, is in the same plane, the dots differing only in size, exactly as in the case of the printing plate. except that the first etching on the matrix is preferably not quite so deep as in the case of the printing plate, as will be apparent by an examination of Figures 1 and 2.

After the first etching, the surface coating of: the matrix is removed, and the ma- 1 rix is agaii'i etched, with the result shown in Figure 3. The entire surface of the matrix is affected the various sized dots being reduced in height in inverse proportion to the areas of said dots. the smallest dots being materially reduced in height, the intermediate dots reduced to a less extent and the large dots being hardly affected at all, whereby an infinite variation in level is provided corresponding to the tone variations in the design. As appears from an inspection of Figure 3, the relatively sharp half tone dots or projections are reduced to relatively smooth projections or waves of different levels corresponding to the dots or tones of the design.

In the case of a matrix made negative with respect to the printing plate, it will be apparent that the effect is exactly the opposite from that shown in Figures 2 and 3; that is, the dark tones and deep shadows, after the first etching, will be represented by small dots and the high lights by large dots or a solid surface, and after the second etching, levels will vary accordingly.

It will be evident to those skilled in the art that by the use of my invention the enormous consumption of time in preparing a matrix by the older systems either to act 7 as an overlay or underlay or for the purpose of distorting the surface of the printing plate under pressure is materially lessened, while by the absolute accuracy of the matrix made according to my invention, a much superior quality and far greater quantity of impressions may 'be taken from a printing plate than has heretofore been possible, since there is much more accurate relative demarcation between the high-lights, intermediate tones and shadows of the plate than is the case in the prior practice, with the result that the blurring which usually takes place after a relatively short use of the printing plate does not occur until after a much longer period of use when my improved matrix is used.

It will be apparent to those skilled in the art that many changes could be made in the details of my invention as I have described the same, without departing from the spirit or scope thereof.

I claim:

1. In the art of printing, the process of making a matrix which consists in reproducing a design in a coating applied to the surface of said matrix, etching the surface of said matrix with a solvent which does not affect said coating, removing said coating from said matrix, and again etching said matrix, whereby the surface of the latter is brought to a plurality of different levels according to the difi'erent light values.

2. In the art of printing, the process of making a matrix which consists in reproducing a half-tone design. in a coating applied to the surface of said matrix, etching the surface of said matrix with a solvent which does not affect said coating whereby the design is formed in the surface of said matrix with a plurality of dots of different sizes but in the same plane, removing said coating from said matrix, and again etching said matrix, whereby the surfaces of said dots are removed in an amount inversely proportional to the size of said dots.

3. A matrix for squeezing the printing surface of a half tone printing plate. said matrix having thereon a plurality of levels corresponding to the tones of said half tone plate.

4. A matrix for squeezing the printing surface of a half tone printing plate, said matrix having thereon a pluralit of projections chemically reduced in ieight to various levels corresponding to the tone values of a predetermined half tone design.

5. In the art of printing, the process of making a matrix which consists in providing a half tone relief on the surface of a metallic plate and treating said plate surface, whiles same is free of resist, with an etching solvent to bring said surface to a plurality of different levels according to the different tone values.

6. A matrix for squeezing the printing surface of a half tone printing plate, said matrix havin thereon a luralit'v of waves of. various heights corresponding to the tones a of a predetermined half tone design.

7. An article of the printing art for cooperation with a half tone printing plate comprising a plate having projections at a plurality of levels in positions corresponding to the dots of a predetermined half tone design.

8. An article of the printing art for cooperation With ahalf tone printing plate comprising a plate having projections in smooth Wave form at a plurality of levels in positions corresponding to the dots of a predetermined half tone design.

Signed at Chicago, Illinois, this 28th day of January, 1922.

EDWARD A. KUNZ.

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