US2362826A - Process of producing dropout half-tone negatives - Google Patents

Description

NOV. 14,1944. A 1 HUTTKAY 2,362,826

PRObESS OF PRODUCING DROP-OUT HALF-TONE NEGATIVES Filed Aug. 25, 1942 IN VEN TOR. ARM L.HUI'71A Patented Now.

UNITED PATENT onnes HALF-TONE NEGATIVES auburn. Huttkay, Newark, N. J. I Application August- 25I1942JSerialNo. 455,934

. l lillain 's.

This invention relates to new and improved processes of preparing printing plates, and' more particularly relates to processes of eliminating all half-tone screening dots inthe background.

or highlight sections of azdrop-out half -tone negative. These processes are particularly adaptable" for the type of photo-engraving and illustration commonly used for newspaper advertising.

An object of this invention is to provide simple processes of highlighting which are free from.

the prevailing lengthy and inexpedient methods, such as laborious hand-painting or hand-' opaquing, or photographing with ultra-violet light, or use of filters, which methodsare in many instances impractical and depend upon de- 'li'cately balanced exposure relationships, and are mostly limited to certain types of drawings. I Another object of thissinvention, is to provide processes which will greatly diminish the] necessity of using skilled labor and which will facilitate the necessary manipulation preliminary to making the printing ,plate.

Still another'object of this invention is to provide processes in whichsubstantially no retouching or finishing operations are performed by hand, thus eliminating the necessityot manipu-' lating wet films and of retouching orjflnishing operations upon the printing plates, and also eliminating'the necessity of making a series of exposures upon these .plates.

. Briefly, the most important characteristic fea ture of all processes proposed herewith is the step 'ofgiving the tone sections of the original draw;

.ing from which the drop-out half-tone negative.

. is to be made,.su h a color that also the lightest portions of these tone sections have a tint to which the light-sensitive photographic material I on which the drop-out half-tone negative is made is-little sensitive. In accordance with a preferred embodiment of the present invention uch sum, I

is obtained. byf'c'oating the sheet on which the original drawing is made with a colorless .coa'tin'g, I

solution 'andpainting the-tonejsections of this drawing with a coloring solution containing in addition to'the paint for creating the shades of these tone sections. an additional'chemical substance adapted to react with the above-coatin solution in such manner as to give at least the i lightest portions of the'tone sections of the drawing the required color, preferably a yellowish, brownish or reddish tint, to which the light-sensitive photOgraphic materiaI on whichthe drop--- out half-tone negative is made, is little sensitive.

From a drawing prepared in this way a drop-put half tone negative can easily be prepared byte photographing this drawing successively through a half-tone screen and without interposing this screen on. a light-sensitive photographic material, preferablya photographic film or plate? after developing the thusexposed film or plate,

a drop-out half-tone negative will appear on it which will have substantially opaque portions corresponding to the high-light sections and halftone portions corresponding to the tone sections of the original drawing. In case that the original drawing also contains line sections, it is easily possible to obtain a combined drop-out halftone and line negative containing, in addition I to opaque high-light portions and screened halftone portions, also transparent portions corresponding to the line sections of the original drawing';-the new processes by which such drop-out half-tone negatives and combined drop-out halftone and line negatives may be obtained will be described below in detail.

It should be noted that throughout this speciflcation and claims, the term high-light sections" is used to designatethose sections of an illustration o'r'drawing which are required to be printed in reproduction as pure white, i. e. free from screen pattern, and is usually used as referring to background or whitep sections of an illustration. The term tone sections" refers to the shaded or dark section of the original illustration or drawing to be printed-in reproduction I The term line sections" refers to the continuous opaque lines appearing on the as half-tones.

original drawing. I

Furthermore, it should be notedthat the term negative is used throughout the specification and claims to. designatephotographic' reproductions on any type of photographic material in which the high-light sections of the original illustrations or drawing appear opaque, the tone sections entirely transparent or white. In the-same ifv'ay, the term positive" designates photographic reproductions on any kind of photographic material, L e. on photographic paper, film or plate, in which the high-light seetions'of the original I drawing are substantially white or transparent;

the tone values of thetone sections substantially the same as in the original drawing, and the line'sectio'ns entirelyopaque; It is evident'that if superimposed negatives are mentioned in the specification and claims, these negatives must consist of .a photographic light-sensitive layer on a transparent base, as for instance photographic films jor plates. I

Finally, it should be noted that the term drawing as used throughout the specification and claims, should not be limited to the exact meaning of the word drawing, but that this term should also comprehend other illustrations, e. g. painted illustrations i1 these are combined with a white background which has to be reproduced without vhalf-tone screening.

The novel features which are considered characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments, when read in connection with the accompanying drawing in which:

Figure 1 illustrates a sheet of drawing paper or like material on which the original drawing is painted; v c Figure 2 represents the sheet shown in Figure 1, coated with the above mentioned colorless coating solution;

Figure 3 represents the original drawing ready for use, consisting of the coated sheet shown in Figure 2 provided with tone sections painted with the coloring solution mentioned above;

Figure 4 shows a semi-finished original drawing of a different type, containing the half-tone sections painted with the above mentioned coloring solution on an uncoated sheet of the type shown in Figure 1;

Figure 5 shows a halt-tone screen of usual type consisting of opaque screening on a transparent base;

tion; all areas in the figures indicated by square 'dots of varying size represent half-tone areas I of the negatives; and finally all areas indicated in derstandable for everybody skilled in this art that further elaborate description may be omitted.

As already stated above, the most important part of the present invention consists in producing the original drawing in a, certain new way not done heretofore. By giving the half-tone sections, especially the lightest portions of these sections of the original drawing, a yellowish, brown or reddish color, or a tint produced by. combination of the above colors, an original drawing may be produced which will enable preparation f the finished drop-out half-tone negative without any drop-out masks or the like. The original drawing tinted as described above has onlyyto be photographed twice on the same light-sensitive material, e. g. film or plate, once with a half-tone screen interposed between drawing and negative material and once without interposing such a screen; the first exposure through the half-tone Figure 6 shows a white sheet of paper used for the flashing step to be described below in detail;

Figure 7 shows a drop-out half-tone negative screen will result in an undeveloped screened negative having latent not visible screening dots in the half-tone portions as well as in the high-light portions of the negative; the second exposure, made without interposing a screen and without intermediate developing of the partly exposed plate or film, will not attack the half-tone portions of the negative plate or film, as the tone sections of the original drawing have a color to which the negative material is only little sensitive; this second exposure will, however, strongly influence the unexposed portions between the screening dots of the high-light portions and cause considerable blackening of the same in the final nega- Figure 8 shows an original drawing having high-light, tone and line sections and being prepared substantially in the same ,way as the original drawing shown in Figure 3;

Figure-9 shows-a semi-finished original drawing having high-light, tone and line sections and being prepared in substantially the same way as the semi-finished original drawing shown in Figure 4;

Figure 10 shows-a drop-out line mask having transparent portions corresponding to the high- In order to facilitate understanding of the above enumerated figures, it should be noted that in the same all white areas represent white highlight sections in the original drawing and white or transparent areasin the'photographic negatives; all opaque areas in the figures represent line sections in the original drawing and opaque areas in the photographic negatives; all areas indicated in the figures by small equally shaped dots represent areas of the original drawing provided with the above mentioned coating solution; all areas in the figures indicated by vertical shading represent half-tone sections of the original drawing, tinted in accordance with the present invenlight and tone sections and opaque portions cortive.

It should be stressed that during this second exposure it is necessary to interpose, between the drawing and the partly exposed plate or film, a

- fully transparent glass plate having the same refraction index as the glass plate used as base for the screen. This is necessary in order to ensure that .the corresponding parts of the images are in register during the first and second exposures.

The blackening caused by the second exposure need not be complete; in any case, it will cause at least a grey, mostly dark grey veil between the screening dots in the high-light portions of the negative which correspond to' the high-light sections of the original drawing. The average blackening of these high-light portions will be sufilcient to avoid appearance of any screening dots on positives produced from negatives made in the above described way.

It should be mentioned that it is necessary to tint the tone sections of the original drawing with colors to which the light-sensitive material used for the negatives is little sensitive; this means that for a specific light-sensitive material specific tints have to be chosen. As most light-sensitive negative materials, particularly those generally used, are little sensitive to yellow, brown and red, it is preferable to use these colors or combinations of the same for painting the tone sections of the original drawing.

It should furthermore be mentioned that it is advisable to expose the light-sensitive photographic materlal through the half-tone screen longer than usual and to make the second exposure without half-tone screen relatively brief so i v at least substantially transparent.

' water.

as'to ensure by the first exposure formation of screening dots in the half-tone portionsof the negative and to avoid any visible influence of the second 'exposure on those half-tone portions.

Finally, it should also be mentioned that it is of advantage to use for developing .the negatives produced in the above way a contrasty developer in order to obtain a strong dark grey veil between the screening dotsin those portions of the negativewhich correspond to the high-light sections of the original drawing while keeping at the same time the areas between the screening dots in those portions of the negative which corresponds to the When the tone' sections of the-drawing are painted with the above mentioned coloring solution, the uranium nitrate contained in the same will react with the sodium thiosulphate contained in the coating solution applied to the drawing sheet and the lighter parts of the tone sections will acquirea yellowish tint to which the generally used negative films and plates on which the drop-out half-tone negatives are made are only little sensitive.

After producing the original drawing in the above described way, the same is first phototone sections of the original drawing entirely or In accordance with a preferred embodiment of the present invention, the partial tinting of the original drawing needed for the new process is obtained by coating the sheet shown in Figure 1 on which the original drawing is to be made. with.

a colorless coating solution,- thereby obtaining the coated sheet shownin Figure 2, and thereafter painting the mne'sections of the drawing with a coloring solution containing, in addition to the paint for creating the shades of these tone sections, an additional chemical substance adapted to react with the'coating solution applied to the sheetshown in Figure 1 in such a manner as .to

give the tone'sections of the drawing or atleast' the lightest portions thereof a tint to which the light-sensitive photographic material on which v the negative -is prepared is little sensitive. An

original drawing produced in this way and having tinted tone sections is shown .in Figure, 3.

It should be noted that it is also possible to paint first on the untreated sheet shown in Figure 1 the half-tone sections with a coloring solution, thereby obtaining the semi-finished drawing shown in Figure 4 and to coat thereafter at least the tone sections of this drawing with the above mentioned coating solution. Also this process will result in an original drawing of the type shown in Figure 3.

It is quite evident and needs no explanation at all for anybody skilled'in this art that there is not the slightest technical difficulty in preparing or choosing two chemical solutions which each per seis colorless which, however, when mixed with each other react as required for the new process proposed herewith, namely result in a yellowish, brownish or reddish tint of the drawing paper to .which both are applied. Therefore the present invention is-fully and sufllciently characterized by stating that ,the coating and coloring solutions used have to be chosen in such a way as to react with each other as stated above.

A preferred? embodiment of the new above describedprocess comprisesthe following steps:

graphed through the half-tone screen shown in Figure 5 and then without this screen. For this latter exposure, the half-tone screen has to be removed without changing the relative position of the drawing and theplate on which the negative is made and a fully transparent glass plate having the same thickness as the glass plate on which the screen-is laid has to be interposed between the drawing and the plate. After this double exposure, the plate is developed in the First the drawing paper shown in Figure 113 coated with a relatively weak sodium thiosulphate solution, e. g. a solution composed of 10 parts of solution containing, besides the grey or black paint generally used, also uranium trate as substance adapted to react in the required way with the above mentioned sodium thiosulphate solution used for coating the drawing'sheet. For

practical purposes, it is preferable to add the uranium nitiate' to the water which is generally used for painting the tone sections of the draw ing, preferably in-a high concentration, e. g. one

- partof uranium nitrate to two parts or water.

a sodium thiosulphate dissolved m 90 parts or I After the thlls produced coated sheet shownin Figure 2 is completely dry, the tonesections are 'painted on this sheet with a coloring;

usual way, preferably using a highly 'contrasty developer, and the drop-out half-tone negative shown in Figure 'l is obtained. I

Sometimes, particularly when the tone sections of the original drawing contain very dark portions, it is necessary to perform in combination with preparingthe drop-out half-tone negative another operation which is universally used and is called flashing. withoiit this flashing, there would be no screening-in the darker portions of the half-tone areasof the negatives because the corresponding sections of the original drawing reflect littleor no light. For this purpose, a

third exposure is made, namely the white sheet shown in Figure 6 is interposed between the original drawing shown in Figure 3 and the halftone screen shown in Figure 5 and photographed on the light-sensitive photographic material. This flashing step then creates the screening needed in the darker portions of the half-tone areas of thenegative.

The process of producing combined drop-out half-tone and line negatives from original drawings containing high-light. ton and line sections is verysimilar to the above described process of producing drop-out half-tone negatives and therefore only the differences between the two processes will be described below in detail. After preparingthe half-tone sections of the original" drawing as described above, the line 7 sections are made in a color to which the light-sensitive photographic material on which the'negative is made is not sensitive at all. Preferably, these sections are painted on the original drawing with black paint or ink which results in. an original drawing of the type shown in Figure8. In the same way asde scribed above in connection with the semi-finished original drawing shown in Figure .4,

it ispossible also in this-case to prepare first the semi-finished drawing shown in Figure 9 and to coatit with the coating solution, e. g. sodium thiosulphate solution, as described above.

The photographic steps for-producing the finished combined drop-out half-tone and line negative shown in Figure 11 from the original drawing shown in Figure 8 are, also the same as described above in connection with making the drop-out half-tone negative I. The only difference between the-photographic steps of the two processes is created by the' fact that, if the flashing operation is used 4 for producing drop-out,

half-tone and line negatives of the type shown in Figure 11, it cannot be performed in the usual way as the screening would appear not only in the half-tone areas butalso inthe line areas'of the negative; the continuity and transparency of these line areas whould thereby be broken up and the object of the present invention defeated.

, aseasae tone sections of said original drawing with acoloring solution containing, in addition to the paint Therefore, it is necessary to make a drop-out line of a transparent sheet provided with opaque portions corresponding to .the line sections of the original drawing. During the flashing step, i. e. during photographing of the white sh'eet shown in Figure 6 through the half-tone screen shown in Figure 5, this drop-out line mask'is placed between the sheet and the screen, avoiding thereby formation of screening dots in those areas of the negative which correspond .to the line sections of the original drawing. v

Although the above .described embodiments are th preferred ones, modifications of the new processes within the limits of the present invention are possible. ThusQfor instance, it is possibie to reverse the photographic steps in all processes where the drawing is photographed consecutively through a half-tone screen and without that screen. It is also possible to reverse the application of the reacting ingredients of the coloring and coating solutions: thus, for instance, it is possible to coat the drawingsheet with a solution containing uranium nitrate and to add sodium thiosulphate to-the coloring solution.

Without further analysis, the foregoing will so fully reveal the gist of my invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or speciflc'aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and f diluted sodium thiosulphate, painting the tone sections of said drawing with a coloring solution containing uranium nitrate in addition to thepaint for creating the shades of said, tone sections, thereafter photographing the thus prepared original drawing successively through a halftone screen and without interposing said screen on said light-sensitive photographic material and also placing, before, between or after said photographic steps,'a highly light-reflecting, preferably white, sheet, in front of said drawings and photographing said sheet through said halftone screen in order to obtain screening dots also in the dark areas of thehalf-tone portions of the I drop-out half-tone negative.

2. A process of producing on a light-sensitive photographic material from an original drawing having high-light and tone sections a drop-out half-tone negative having opaque portions corresponding to said high-light sections and halftone portions corresponding to said tone sections,

- said process comprising the steps ofpainting the a for creating the shades of said tone sections, also uranium nitrate, coating at least the thus prepared tone sections or said original drawing with asodium thiosulphate solution, thereby causing reaction between the uranium nitrate contained in said coloring solution and the sodium thicsulphate and thus giving at least'the lightest portions of the tone sections of said drawing a yellowish tint to which said light-sensitive photographic material is only little sensitive, thereafter photographing the thus prepared original drawing successively through a half-tone screen and without interposing said screen on said lightsensitive photographic material and also placing, before, between or after said photographing steps, a highly light-reflecting, preferably white, sheet in front of said drawings and photographing said sheet throughsaid half tone screen in order to obtain screening dots also in the dark areas of the half-tone portions of the drop-out halftone negative.

3. A process of producing on a light sensitive photographic material from an original drawing having high-light and tone sections a drop-out half-tone-negative having opaque portions corre-- 'sponding to said high-light sections and halfthe paint for creating the shades of said tone sections'also uranium nitrate, causing thereby-a reaction between the uranium nitrate contained in said coloring solution and the sodium thiosulphat'e and thus giving at least the lightest portions of the tone sections of said drawing a yellowish tint to which said light-sensitive photo-- graphic material is only little sensitive, thereafter photographing the thus prepared original drawa ing successively through a half-tone screen and without interposing said screenon said lightsensitive photographic material and also placing, before, between or after said photographing steps,

a highly light-reflecting, preferably white sheet in front of said drawings and photographing said sheet throughsaid half-tone screen in order to obtain screening dots also in the dark areas of the half-tone portions of the drop-out half-tone negative. v 4

4. A process of producing on a light-sensitive photographic material from an original drawing having high-light and tone sectionsa drop-out half-tone negative having opaque portions corresponding to said high-light sections"and halftone portions corresponding to said tone sections, said process comprising the steps of applying to that surface of a drawing sheet on which said original drawing is to be made a solution containing uranium nitrate, painting onthe thus treated drawing sheet the tone sections of said I the lightest portions of said material-is slightly sensitive,

' out hali-tone and line negative portions corresponding to said high-light sections,

' black, and tinting posing said screen on said light-sensitive photo graphic material and also placing, betore,'be-

tween or after said steps of making an original drawing with line sections or a color to which said light-sensitive photographic material is not'sensitive, preferably black, and tone sections of such a color that also tint to which said light-sensitive photographic making also, in addition to said original drawing, a drop-out line mask consisting of a tr nsp'arent sheet having opaque areas corresponding to the line sections of said original drawing, photographing said original drawing througha half-tone screen, photographin'g thereafter a h hly light-reflecting, preferably white,

line' mask interposed between with said drop-out said white sheet and said screen, and ,flnally said light-sensiphotographing said drawing on tive photographic material directly, interposing neither said screen nor said mask 6. Process of producing o ight'y-sens'itive photographic material, from an original drawin having high-light, line and tone sections a drophaving opaque transparent portions corresponding to said line sections and half-tone portions corresponding to -said tone sections, said process comprising the stepsof making the line sections of the original color to which said light-sensitive material is notsensitive, preierably the tone sections of said original drawing in such a manner that also the lightest portions of said tone sections have a tint'to drawing of a photographic a light-sensitive sheet through said half-tone screen.

said original drawing, a drop-out line mask coniii having high-light, line and tone sections a drop-.

which said light-sensitive photographic material is only little sensitive. making also, in addition to sisting of a transparent sheet having opaque areas corresponding to the line sections of said original drawing, photographing said original drawing through a half-tone screen, photographing thereafter a highly light-reflecting, preferably white, sheet through said half-tone screen with said drop-out line mask interposed between said whitesheet and said screen, and finally photographing said drawing on said light-sensitive photographic material directly,.interposing neither said screen nor said mask. r

'7. Process of producing on a light-sensitive photographic material from an original drawing out half-tone and line negative having opaque tone sections have a portions corresponding to said high-light sections, transparent portions corresponding to said line sections and half-tone portions corresponding to said tone sections, said process comprising the steps of coating the sheet on which said original 7 7 drawing is made with a colorless coating solution, painting the tone sections of said drawing with a coloring solution containing in addition to the paint for creating the shades of said, tone sections an additional chemical substance adapted to react with said coating solution in sucha manner as to give at least the lightest portions of the tone sections of said drawing a tint to which said lightsensitive photographic material is little sensitive, making the line sections of said drawing of a color to which said light-sensitive photographic material is not sensitive, preferably black, making also, in addition to said original drawing, a drop-out line mask consisting of a transparent sheet having opaque areas corresponding to the line sections of said original drawing, photographing said original drawing through a half-tone screen, photographing thereafter a highly light-reflecting, preferably white, sheet through said half-tone screen with said drop-out line mask interposedbetween said white sheet and said screen, and finally photographing said drawing on said lightsensitive photographic material directly, interposing neither s'aid screen nor said mask.

ARTHUR L. HUTTKAY.

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