US1618534A - Art of halftone photoengraving color printing - Google Patents

Description

B. F. HUTCHISON ART OF HALFTONE PHOTOENGRAVING COLOR PRINTING Filed Feb. 5. 1922 4 sheets-sheet 1 fnoezuor [[JzZzzess Bcw a'mmZZ z zt'eizsmz 1,618,534 1927' B. F. HUTCHISON ART OF HALFTONE PHOTOENGRAVING COLOR PRINTING Filed Feb. 5, 1922 4 Sheets-Sheet 5 lmmmlllll lllllflflllllll umumu mluumlll Patented Feb. 22, 1927.

UNITED STATE-S PATENT o ncE.

ART OF HALFTONE PHOTOENGRAVING COLOR iBINTI'NG.

Application filed February 3, 1922. Serial No. 583,872.

This invention relates to prints produced by impressions of a ke plate and a supplementary plate with dlflerent colored inks.

An object of the invention is to produce two-color prints of this character havmg finer and more delicate effects than it has heretofore been possible to produce by half tone photoengraving processes.

An object is to produce two-color prints having intricate tracings, such for instance, as forest scenes with cloud effects visible through intricate foliage in which the tracin s of the leaves across the sky with cloud efiicts will be too diflicult to produce artistically in any mode of halftone photoengraving heretofore known.

This invention may employ a method of preparin camera copy for a supplementary late to e used for producing impressions in conjunction with those of a key plate, in which method the camera copy is painted upon one side of a transparent sheet of celluloid, upon the other side of which is an impression of the key plate; so that the key plate impression may serve as a guide viewed through the celluloid for determining the places where the paint is to be applied, and no claim is made herein to such method broadly as the same is described in my application Serial No. 526,523, filed January 3, 1922, for improvements 1n the art of photo gravure color printing.

The present invention is broadly new, basic and pioneer in that I make up a composite camera copy consisting of what I term a mesh copy forming a back-ground of an actinic color, and a transparent blotter made upon a transparent sheet and contain ing an opaque practically non-actinic impression of the key plate, through the 1n terstices of which impression, said back ground can be photographed so that the tracery formed by the interstices of the key plate impression will appear in the negative from which the supplementary plate is to be made.

By this means it is possible to produce upon the negative any desired application, either to minimize or to intensify the image of the camera copy wherever desired; and to introduce efi'ects behind open foliage and traceries or detail of the key plate as well as to introduce solids which when printed by the supplementary plate superpose color in the finished print thereby enabling vacolor by the impression of the supplementary plate in the finished print.

The blotter or separation sheet comprising an opaque non-transparent impression of the key plate on the transparent sheet of the camera copy, serves to blot out from the camera copy those parts of thekey plate which are not to be reproduced in the supplementary plate, and it may also serve as a medium upon which the workman may lay tints or tones to increase, to diminish, eradicate or superpose color in the impression of the supplementary plate, in the finished print.

An object is to enable the workman to so operate that the color from the supplementary plate will mesh with that from the key plate in the final print.

An object is to enable the workman to use an air brush upon portions of the camera copy for the supplementary plate which must mesh with the key plate, thereby attaining a greater smoothness of tone and delicacy of shading.

In this description I use the term key plate to designate that original half-tone printing plate which is intended to be used for printing one 'of the colors in a two color half-tone print; and I use the term mesh copy to indicate an element of the camera copy that is to mesh with, but not overlap, color from the key plate; and I use the term trap copy to designate that element of camera copy which is to produce c(1 lor to superpose upon color from the key ate.

P I use the term actinic and non-actinic to indicate, respectively, those colors which on the one hand, are susceptible, and on the other hand are negligibly susceptible to photography by the wet plate process in use by photo-engravers without the use of color filters.

Heretofore it has been impracticable to make a satisfactory half-tone supplementary printing plate from an impression or print of a half-tone printing plate, for the reason that the print consisting of half tone dots, when photographed through a half-tone screen, breaks up such dots in the negative and gives muddy elfects and produces what is known to photo-engravers as screen patterns.

An object of this invention is to avoid such difliculty and to enable the photo-engraver to make a superior half-tone supplementary plate from a half-tone print. This I' do by making a negative for the supplementary plate by photographing a back-ground through the interstices of the print while the dots of the print are covered with a substantially non-actinic blotter without covering certain interstices of the print.

It is understood that the blotter' may be formed by one or more impressions so as to build up the same; and that such impressions may be on ve thin transparent sheets, respectively, so t at the sheets and im ressions are practically a unit.

I n object is to produce camera copy for a supplementary half-tone printin plate in a mainly'mechanical way; and this. is effected by using an impression or impressions of'the original late in non-actinic ink as a basic portion 0 such camera copy.

An object is to cheapen the production of camera copy for the supplementary color plate of two-color printing plates.

An object is to so produce camera copy for the supplementary color plate of twocolor printing plates as to reduce the need of re-etching the supplementary color plates and to thereby cheapen the work of engraving. Y

,An object is to make a. supplementary half-tone printing plate from the impression of a previously made half-tone printing plate, so that when the-two are printed on a common surface the resultant print will be similar to a duotone. V

This invention includes a method by which a half-tone supplementary printing plate may be made from the impression of a previously made half-tone printing plate.

A principle of this invention .is that by usin a transparent sheet having thereon a su stantially opaque and non-aetinic imression of the ke plate, it is possible to insure the elimination from the supplementary plate of practically all of the image from the key plate except the portion or portions thereof where color is applied b the workman to the camera copy.

In this method of preparing camera copy, the color therefor may be laid upon the blotter or transparent sheet containing the substantially opaque non-actinic impression of the key plate on the reverse side of the sheet from the key plate impression, or upon a separate sheet placed at theback of the opaque impression and which sheet forms a trap color copy sheet. It said oqaque impression is placed between the non-actinic key plate impression which forms the mesh copy and the camera, the color plate made from the camera copy thus made, will exactly mesh with the image in the key'plate; and if the color laid upon the opaque impression, or upon a transparent sheet is between the opaque impression and the camera, a reproduction from the camera copy may be made to trap, or to superimpose upon, the color in the key plate. Color laid back of the opaque impression of the key plate will automaticallv mesh with the color from the key plate in the finished print; and color laid in front of the opaque key plate impression may be made to superimpose or trap color from the key plate in the finished print.

An object is to produce a two-color halftone print of .intricate design with a distinct separation of color.

Other objects, advantages and features of invention may appear from the accompanying drawings the subjoined detail description and the appended claims.

The invention may be understood by reference to the accompanying drawings which illustrate the final prlnt and certain paraphernalia used, and different results obtained in the course of making the final print by the preferred method in which the camera copy is made up of three sheets.

Figure 1 is the mesh copy sheet which is to form a back-ground component of the assembled camera copy, and which, in this instance is a sheet of red paper with an impression of the key plate in a different color that may or may not be non-actinic.

Fig. 2 shows the mesh copy sheet with inserted mesh copy thereon.

Fig. 3 is the blotter or separation sheet which is a transparent sheet with a substantially opaque and non-actinic key plate impression, which, in this instance is blue. This sheet serves as a filter or mask in the com letedcamera copy.

Fig, 4 is the trap copy sheet; the same being a transparent sheet with an impression of the key plate in red ink to be used as a. guide print in producing the trap, or superimposed color portion of the camera copy.

Fig. 5 is the camera copy trap sheet, being the same sheet shown 1n Fi 4 with the tra or superimposed copy t ereon; and omitting the image of the ey plate which has been erased.

loo

Fig. '6 is the completed and assembled camera copy consisting of mesh copy shown pose of impressions from the key plate and actinic basis.

supplementary plate indicated in the preceding views.

The method for producing supplementary plates by this process is as follows:

The workman is provided with the customary brushes, air brushes and other artists equipments, not shown, and proceeds with the work as follows:

First An impression 1 of a key plate, not sli wn is made upon mesh copy paper 2, as in 1g. 1; and such impression constitutes the mesh copy guide, adapted to form a background for the camera copy and enable the workman to see where to paint for increasing or decreasing the intensity of color or for eliminating color in the mesh copy; or for making additions to the mesh copy.

I prefer to use red or yellow mesh copy paper with the mesh copy guide impression of the key plate in blue ink for the reason that such image of the key plate can be clearly distinguished by the eye of the workman and is at the same time of a non-actinic character; and the red or yellow mesh copy paper forms a background having a satisfactory Other colors however, may be used.

Second: The workman may then paint either with actinic or non-actinic color any of that portion of the camera copy which is to mesh with the key plate impression in the final print 3 shown in Fig. 8, and he may make additions to the camera mesh copy such as the clouds 4 shown in Fig. 2. He may thus, by the use of white a, and color 6, eradicate, diminish or increase any portion of the color in the mesh copy sheet and he may use i an air brush in portions of this work thereby modulating the key plate impression as desired.

Third: An impression 5 of the key plate is then made upon a transparent sheet 6,

(Figs. 3 and 6) in a substantially opa ue non-actinic ink; either white or blue. T is sheet, so prepared, forms the blotter or separation sheet.

Fourth: A second transparent sheet 7 shown in Fi s. 4, 5 and 6 is then printed with a red in impression 8, (Fig. 4) of the key plate. This constitutes a guide print for use in the work ofv producing the camera copy of such portions of the color in the supplementary plate as will trap or be superimposed upon color from the key plate in the finished print 3. Such portions are indicated at 9, in Figs. 5 and 6, and are adapted to produce secondary colors in the finished print. This constitutes the tra color copy sheet 7 shown in Figs. 4, 5 and 6, and may be printed on said sheet 7 in any color of ink, preferably red.

Fifth: The workman reverses this trap copy sheet turning it with the impression 8 of the key plate toward his drawing board, not shown, thus bringing into View through sheet 7, the impression 8 of the key plate;

and the workman then uses said impression 8 as a guide to show where to paint his camera copy in order to produce trap or superimposed color 9. He may also paint such portions of mesh copy as is desired.

Sixth: When the workman has completed the painting of the copy for such trap color, he erases the guide print 8 and the resulting sheet 7 with the painting 9 thereon constitutes the camera trap copy as shown in Figs. 5 and 6.

Seventh: The workman then assembles the mesh camera copy sheet 2, the blotter or separation sheet 6, and camera vcopy trap sheet 7, with the camera copy trap sheet. nearest the camera, and next to it, the blotter or separation sheet, and further from the camera, the mesh copy sheet. This assembled camera copy shown in Fig. 6, is then photographed in the ordinary way, preferably using a prism attachment to the camera. Then the negative is developed and printed, and the metal etched in the customary manner of producing half-tone photo-engravings, the result being an actinic halt-tone printing plate, an impression 11 of which is shown in Fig. 7. When such impre3sion and an impression of the key plate are printed upon a common surface in different colors of ink, a two color or duotone print 3, shown iin Fig. 8, is produced.

An application of this principle may he made by omitting the trap cop'y sheet, Fig. 4, and painting trap copy upon the face of the opaque impression 5 of the key plate upon the blotter or separation sheet 6 and then proceeding to assemble and use the blotter or separation sheet and the mesh copy sheet 2, in the same manner as described in the preferred method.

The preferred method has the following advantages over this alternative application, in that the trap copy can be more accurately painted upon the separate trap copy sheet shown in Fig. 4, than it can upon the blotter or separation shcct, shown in Fig. 3; becausethe image of the key plate is much clearer when printed'in red ink or other strong color. If the work is done upon the blotter or separation sheet, the impression of the key plate is more difficult to distinguish. Another advantage is that the trap copy being photographedthrough the transparent sheet gives a negative, and consequently a printing plate that is freer of brush marks and imperfections than if the trap copy were painted upon the blotter or separation sheet.

Another alternative application is by painting trap copy upon the blotter or separation sheet as described in the above alternative method and then painting the mesh copy upon the back of the blotter or separation sheet; this latter application has, in addition to the disadvantages above described, the further objection of confusion of detail as the work of pa nting progresscs, and it is impossible to thus produce camera cop of as accurate actinic value as can be pro uced by the preferred method.

In any of the three methods of application described I use a sheet of thin transparent celluloid wherever a transparent sheet is mentioned in this description.

I claim:

1. The method set forth of producing camera copy comprising first printing on a transparent sheet a substantially opaque and actinic impression of a half tone printing plate; and then arranging said sheet in front of a background of color when exposed to a camera thereby defining the interstices through which the background may be photographed.

2. The method set forth of producing camera copy comprising first producing on a transparent sheet a substantially opaque actinic impression of a printing plate; then applying to a sheet having nonactinic base,

an air brush application of color to modify the nonactinic character of said base; and then assembling said nonactinic base behind the transparent sheet so that said base may be photographed through the interstices of the impression 3. The method set forth of producing camera copy which method comprises printing a substantially opaque actinic impression of a half-tone printing plate upon a transparent sheet; then printing upon one side of another transparent sheet another impression of said plate to form a guide print; then applying color to the reverse side of said other sheet; then erasing the guide print to form a trap color copy sheet; and then assemblingsaid opaque impression in back of said trap sheet and in front of a non-actinic base.

4. The method set forth of producing camera copy, which method comprises printing upon a transparent sheet a substantially opaque actinic impression of a half-tone printing plate; then using an air brush upon a background for the purpose of introducing into the finished print delicate shadings of color which will mesh with and print in register but will not overlap delicate traceries and intricate designs in the final print from the original plate; and then superposing the transparent sheet with the impression of the plate to be supplemented, between the background and the camera when the copy is to be photographed.

5. In the art of multi-color printing the method set forth of preparing photo-engravers camera copy for producing a supplementar half-tone printing plate adapted to be use in conjunction with a photo-engraved half-tone printing plate made at a previous time, to produce when the two are printed upon a common surface in different colors of ink, a print similar to that known to photo-engravers as a duotone; which method comprises printing upon a transparent sheet, an impression of the photo-engravmg for which the supplementary printing plate is to be made; such impression being in substantially opaque aciinic ink for the dual purpose of serving to blot out the solids and in a lesser degree, the middle tones represented in the icture in the half-tone photo-engraving or which the supplementary plate is to be made, and to blot out that portion of the color which may be introduced by the workman and which would otherwise superpose upon color from the key plate in the finished print where it is not desired; then painting upon the reverse side of the transparent sheet from that upon which the opaque impression is made to produce color which is to mesh with color in the key plate; then applying color to the side upon which the opaque impression is made to enable color to be superposed upon color from the key plate.

6. The method set forth of preparing camera copy for a photo-engraved half-tone printing plate to supplement 9. previously made half-tone printing plate which consists in printing the two plates in different colors of ink to form, a two color print similar to that known to photo-engravers as a duotone will be produced; and, preparing such copy in three separate units and assembling them before the camera as set forth.

7. The composite camera copy set forth comprising a non-actinic background having an impression made of half-tone dots; a transparent sheet having a substantially opaque actinic impression made of half-tone dots and arranged so that the dots on the background are covered without covering certain interstices of the background to permit said uncovered interstices to be photographed.

8. The composite camera copy set forth comprising a transparent sheet havin a substantially opaque actinic impression t ereon; a non-actinic background behind said sheet and adapted to be photographed through the interstices of said impression; and a sheet having a forced application of color to modify the non-actinic character of said background.

9. The method set forth of producing Ill impression of a key plate thereon; a transparent sheet having an impression of said ey plate thereon; and another transparent sheet having a painting thereon to produce trap color.

11. The camera copy set forth comprising a sheet of a non-actinic character having an impression of a key plate thereon; a transparent sheet having an impression of said key plate thereon; and another transparent sheet having a painting thereon to roduce trap color, said copy being assemble so that said first mentioned transparent sheet is between the non-actinic sheet and the trap color and said trap color being arranged so that When the copy is photographed the trap color will be photographed through the sheet upon which it is applied.

In testimony whereof, I have hereunto set my hand at Los Angeles, California, this 26th day of January, 1922.

BENJAMIN FRANKLIN HUTCHISON.

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