US1885725A - Method for making multicolor printing plates - Google Patents

Description

NOV. l, 1932. Q s, HOWLAND 1,885,725

METHOD FOR MAKING MULTICOLOR PRINTING PLATES Filed Oct. 8. 1929 2 Sheets-Sheet 1 /Me d//be Nov. 1, 19,32.

Hofe /md e Reversed.

Filed Oct. 8. 1929 reversed.

Figl f 2 sheets-sheet 2 )5MM MWYM? Patented Nov. 1, 1932 GERALD S. HOWLAND, F BROOKLINE, MASSACHUSETTS j METHOD FOR MAKING MULTICLOR PRINTING PLATES Application led October 8, 1929. Serial lNo. 398,275.

This invention relates to amethod for making multicolorprinting plates for reproduction in color.

Heretofore in making plates of theforegoing character, it has been customary to take a series of photographs of the subject using different color filters and a half tone screen` turned at different 'angles to prevent patterning in order to secure negatives equal in number to the number of color plates to be-made. In taking these photographs, a prism is used in order to secure negatives with the images unreversed. From each negative a plate of suitable material permitting etching, such as copper, covered with a sensitized coating, is

l commands very high wages. In spite of this printed which gives a positive impression of the. subject with the imagein reversed position'so that when the plate is used for printing, the impression of the subject therefrom will be in unreversed position. The plates so prepared are then etched in any suitable manner and are proven after each etching by taking a color impression therefrom and this process of alternate etching and proving is continued until satisfactory results are attained. Since the etching in each case is a' question of judgment and calls for the exercise of a high degree of skill, the number of those who are qualiiied to do this work is limited and skilled etchers or color engravers are in great demand and receive large compensation.

generally only one man can do the etching on a set of plates since he carries the color scheme in his mind and all the plates must be made in accordance with this scheme and the process is expensive because the great skill and judgmentrequired of the etchers skill, however, mistakes of judgment are not of infrequent occurrence and when any etching results in too much of the material of the plate being removed it is thereby rendered valueless and the work has to be started'over from the beginning. As a general rule not less than six days are required for the preparation of a set of four color plates and sometimes this period is extended to two or three weeks according to the character of the subject and the plates. The Work consumes much time with ever present possibilities of lover-etching with the burden in such cases of throwing away the work and beginning the process anew. Another disadvantage of the old method is that if a set of plates of a different size is required of the same subject, the

entire method has to be repeated for each size ofpla-te because the making of one sized set is of no assistance in turning out a different size and because of this fact another disadvantage creeps in, na1nely,cthat there is a difference between the fina-l result secured in different sizes of sets of plates of the same subject since it is simply impossible for the engraver to produce the same identical results in different sizes.

One ofthe important objects of the present invention is the provision of a method` of making multicolor plates which is more expeditious, more exact .in results and cheaper.

Another object of the invent-ion lis the provision of a method by which certain steps are obviated in the preparation of vone or more sets of plates of thesame subject ydiffering in size from theA original set so that additional ,sets of dii'erent sized plates may be produced at a greatly reduced cost.

A further object of the invention is the` production of a method which does not require highly skilled etchers 0r color engraversto produce the desired results and thereby .cuts substantially the labor costs in the preparation of the plates.

An additional object is the provision of a method which obviates most-of the possibility of over-etching` and thereby eliminates waste.

Qther objects of the invention Will be more specifically set forth and described hereinafter. n y

`In the laccompanying drawings, there is sh own a flow sheet to illustrate the procedure followed in carrying out my processfor .the reproduction of a subject in color by the use of four plates, in which Figure 1 shows the first four steps of the process beginning with the photographing of the subject using color filters and Fig. 1a shows the last three steps ending with the printing of the reproduction by the use of the four plates prepared in accordance with my invention, that part of the y flow sheet shown in Fig. la being a continuation of the fiow sheet shown in Fig. 1. FollowingT is a detailed description of the process shown in the accompanying drawings.

One of the essential features of my process consists in first preparing a set of prints in black and white of the subject, correspomling in nlnnbcr to the iilunber of plates desired, which prints when retouched are used as a record from which 'any number of sets of plates of different sizes may be prepared.. To secure this recorda series of photographs of the subject are taken using any suitable photographic apparatus in order to obtain a series'of negatives equal in number-to the number of plates to be made. In taking this series one black and white View is taken without a color filter' and the balance ofthe series are taken using different color filters. For example, if four plates are to be prepared, one photograph is taken without a color filter, one with a green filter which eliminates all colors iii-the subject except red, one with `an orange-red filter eliminating all colors except blue and the last with a violet filter which cuts out all colors except yellow so that as a result of the four photographs, one has four negatives showing separately the black and white, the red, the blue and the yellow color values in the subject. I

From the four negatives, a set of four prints in black and White is then made, said prints being mounted upon cardboard or other suitable support either in assembled relation or separately as desired. For making the prints any suitable photographic printing paper may be used but care must be taken to avoid any stretching of the paper when mounted on the support sol thaty there will be perfect register in the finished plates. The

prints or photographs are then retouched in black andwhite to bring out the effects desired or to emphasize some points and to minimize others, the artist supplementing the work of the filters, since color filters generally are only theoretically correct and do not always give absolutely correct results. The retouehing corrects the deficiencies of the filters and the photography and in the retouching theartist has before him the subject as a criterion. If, in some cases the color filters produce satisfactory results, retouching may be avoided which might be true of cheaper classes of work but as a rule in graphing each print througha half tone or other screen of suitable mesh using a prism lens to secure the image on the negative in unreversed position. 'lo prevent patterning the prints are turned at ditl'erent angles when photographed, from each negativcis taken a print on a plate of material suitable 'foi' etching or engraving, such as copper, said plate being coated with a suitable sensitized preparation for this purpose. y"Since the image on the negative is in `unre\'ersed position, the image on the plate will be apositive reversed in position so that impressions from the plate will appear nni'eversed and like the subject. The plate is then developed and is geneially baked in the well-known manner to fix. the image thereon.

The plates so prepared are then ready ior etching or engraving and in this work the ctchei' or engraver follows. the record prints to bring out in the plates the-color -,values shown in theI prints in black and white. lhis operation thereupon becomes merely a question of matching in the plate the light and shade values as shown inthe record and this work does not call for the high degree of skill and judgment required vin etching plates by the old process whent-lieyetcher or engraver had to carry 'in his mind in etching cach plate the color sehemeofLthe finished product, but can be adequately performed by operators whose pay isnot more than half that called for by theold n-iethod.

` In preparing plates by this method the four plates, for instance, in i'our color work, can be given to four difl'erent operators, as eaclroperator has merely the. simple problem of treating the plate to bring out thevalues shown in his particular record print. thercbybeeomes possible to produce a setof plates in a milch shorter time than under the old method in which all the work had to be done by one man. i y,

'When the record prints are small in size they may all be mounted on one support of cardboard or other suitable material but in such case the prints are mounted at different angles to each other to prevent patterning being caused in the impressions taken from the finished plates due to use of the half tone or other kind of screen. When so mounted in assembled relation, all the prints may be photographed as a unit and all printed from.

the negative onto the sensitized plate in one operation thereby saving time, labor and materials. The plate either before or after being etched may be cnt into the separate plates.

When one or more additional sets of plates of the same subject but of other size or sizes is or are required, they are prepared by photography from the record prints following the method hereinbefore described by either enlarging or reducing the sizes of the negatives in comparison with the record prints.

All)

It is' to be observed that the retouched prints which serve as a record operate as a lcontrol of the process which gives a most accurate'measure of color values to facilitate the etching o1" engraving and an accuracy far greater than the old process.

The advantages of my method are first, that it eliminates the use of highly paid color etchers or engravers thereby greatly reducv ing the cost of the plates; secondly, the

method can be carriedout in a shorter time and is more expeditious and where the old method required six days or more for the production of a set of four color plates, the same may be produced Within twenty-four hours from the' preparation of the record photographs. I have found that the expense of preparingthe first set of plates including the preparation of the record prints runs from thirty to thirty-tive percent less than the preparation of the first set of plates under the old method and that the cost of preparing subsequent sets of different sized plates is reduced fifty percent over the cost of those plates prepared by the old method. Thirdly, because the retouching is done on the black and white photographs or prints, better resul-ts can be secured, the Work canbe done more easily and it can be done by women as well as men and in a much shorter time. In carrying out my method the results desired in the finished plates are shown on the record prints whereas under the old method it was done by the color engravers in the etching Y room working over acid and under unfavorable conditions.

. My method will be found especially valuable in the making of plates such as are used in the chromium process where it is impossible to re-etchand the desired results must be attained in the first etching because my negatives the images of said prints in unreversed position, said prints being arranged at different angles when photographed to avoid patterning, then printing from said negatives upon sensitized plates suitable for etching andfinally etching said plates to obtain the respective color values shown in said retouched prints.

2. The lnethod of making multicolor printing plates for reproduction in color consisting in making a series of photographic negatives, one in black and white and the others with various color lters, said negatives corresponding in number to the number ofplates desired, preparing a print from each of said negatives, then mounting said prints on a single sheet of suitable supporting material in close and angular arrangement to prevent patterning when photographed through Va half-tone screen, then preparing a photographic negative of said series of prints, using a suitable half-tone screen with a prism lens for securing on said negative the images of said prints in unreversed position, then printing from said negative upon a sensitized plate suitable for etching, etching said plate to secure the respective color values shown in said retouched prints and finally cutting said process practically makes unnecessary rel etching.

It is to be understood that my method is susceptible of use in making plates for reproducing by various other processes and that the plates may be of different materials and of different forms and where in the following claims I use the term plate I intend it Vto include plates either iii fiat, cylindrical or other forms. c.

What I claim is:

1. The method of making' multicolor printing plates for reproduction in color consisting in making a series of photographic negatives, one in vblack and white and the others with color filters, said negatives correspondin black and white the color values of the prints, using auitablehalf-tone screen and with a prism lens forsecuring upon said respective colors in the subject, then prepar.- p ing photographcnegatives of said series of

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