US2601161A - Medium for use in making camera copy and method of preparing the same - Google Patents

Description

June 17, 1952 M. D. MOINTOSH 2,601,161

MEDIUM FOR USE IN MAKING CAMERA COPY AND METHOD OF PREPARING THE SAME Filed Aug. 19, 1948 INVENTOR. MAURlCE D. M INTOSH ATTORNEY Patented June 17, 1952 MEDIUM FOR USE IN MAKING CAMERA COPY AND METHOD OF PREPARING THE SAME Maurice'D. McIntosh, ClevelandHeights, Ohio, assignor to Louis S. Sanders, Shaker Heights,

Ohio

Application August 19, 1948, Serial No. 45,058

4 Claims. (Cl. 41-41) This invention relates, as indicated, to a medium for use in making camera copy, and to a method of preparing the same.

In my Patent No. 2,355,884, I have described a drawing paper in which one pattern in the form of small dots, is superimposed over another, in the form of larger dots, both patterns being formed in such a manner that registry between two different printing plates, as described in my Reissue Patent No. 20,503, is not necessary. The method involves separate and distinct steps forapplying the chemicals constituting the two dot patterns, and also involves a step of removing a varnish imprint with a solvent, as well as certain other procedural difficulties.

I have discovered that I can eliminate one or more of the steps heretofore thought necessary in making a drawing medium of the character described, while retaining the advantages of such a medium, particularly the advantage of perfect registry or proper relative location between the difierent patterns, by preparing the medium in accordance with the method to be now described.

The invention can probably best be understood by reference to the accompanying drawing, wherein Fig. 1 is a perspective view of a fragment of a base sheet which is used for preparing the medium of the present invention;

Fig. 2 is a fragmentary elevational view of the base sheet of Fig. 1, but showing the application of the dots in accordance with the first step of my method;

Fig. 3 is a fragmentary cross-sectional view, taken on the line 3-3 of Fig. 2;

Fig. 4 is a view similar to Fig. 2, but showing the manner in which the second series of dots is formed;

Fig. 5 is a fragmentary cross-sectional view. taken on the line 5-5 of Fig. 4;

Fig. 6 illustrates the production of one tone value by development of the smaller series of dots, and

Fig. 7 illustrates the production of a greater tone value by development of both series of dots.

Referring more particularly to the drawing, and especially to Fig. 1, i represents a white paper base sheet, which is provided on one or both sides thereof with laminations or coatings 2 of a colorless water-impermeable material, such, for example, as cellulose acetate, cellulose nitrate, ethyl cellulose, vinyl acetate, vinyl chloride, and the like.

One of the laminations or coatings 2 is coated or covered with a very thin lamination or sheet 2 1 3 of a non-moisture-proof cellophane or a gelatin coating, which cellophane or gelatin should be insoluble but permeable to water solutions.

Instead of utilizing a cellophane covered base sheet, as described, I may, if I so desire, start with a sheet of unmounted cellophane of the character described.

Then, by means of a printing plate, as used in ordinary letter press printing, I apply to the cellophane or gelatin surface, a pattern of dots 4, which, as shown in Figs. 2 and 3, are circular, but may be square or any other desired shape, the dots being spaced from each other in a manner similar to the spacing of dots in an ordinary Ben Day pattern. Such dots, in actual practice, are extremely small and spaced very closely together, but the size and spacing are greatly enlarged in the present drawing, for purposes of clarity.

The ink or solution, of which the dots 4 are composed, contains the following ingredients:

- Grams LePages Liquid Glue -4 48 Glycerin 24 Mercurous chloride -l 350 Water f :50 Diethylene glycol Cobaltous chloride (Co C12.6H2O) The ingredients forming this ink are milled on a conventional stone mill or 3 roll mill.

After a short interval of time, the merourous chloride which cannot permeate the cellophane or gelatin, remains in its in situ or applied position, on the surface of the cellophane or gelatin. and does not become enlarged. It forms the small circular dot 5, shown in Figs. 4 and 5.

During this time interval, the cobaltous chloride, which is permeable in the cellophane or gelatin, migrates or diffuses into the cellophane or gelatin, and spreads uniformly in all directions therein, forming the larger circular dots 6, shown in Figs. 4 and 5, on which e dots 5 are superimposed.

After the dots 6 have grown to a desired size, and suflicient contrast between the respective dots 5 and 6 has been obtained, the dots are fixed by means of a fixing agent consisting of the following ingredient Parts Sodium tungstate (Na2WO42I-I2O') 1U Formalin (40% formaldehyde) 5 Water This fixing agent, through double decomposition, precipitates the soluble cobaltous chloride as 3 insoluble cobaltous tungstate, which prevents further migration or enlargement of the dots 6. At the same time, the formaldehyde in the Formalin insolubilizes the glue vehicle of the ink, thereby binding or fixing the mercurous chloride dots 5.

The length of the time interval between the printing and fixing steps will determine the relative size of the dots and accordingly the relative tone value of the patterns. The superimposed dots must necessarily be smaller than the underlying dots in order to secure a useful difference in the final tone values.

The medium, as thus prepared, exists as a cellophane or gelatin film, containing a white (actinic color) insoluble chemical dot pattern consisting of a series of uniformly spaced dots 6 of cobaltous tungstate, and a series of mercurous chloride dots superimposed upon the cobaltous tungstate dots and of a smaller uniform size, the superimposition of one series of dots upon another resulting in an exact registration or proper relative location between the dots.

The medium thus prepared is the medium of the present invention for use in making camera copy.

After a suitable drawing, as for example, an ink line drawing, has been made upon the medium, one or both of the patterns may be developed in desired areas as a shading of or accompaniment to such line drawing.

In order to develop the dots 5, a chemical developer consisting of a 5% aqueous solution of thiourea is applied to the sheet, as by means of a brush, thereby changing the mercurous chloride dots to a black or brown non-actinic color and producing a Ben Day tone of one value, as shown in Fig. 6. In order to develop a tone of a deeper or darker value, a chemical developer consisting of a 4% aqueous solution of sodium sulphide is applied to the sheet, as by means of a brush, thereby changing both the cobaltous tungstate and mercurous chloride dots to a black or brown color, and producing a Ben Day tone of greater value, as shown in Fig. 7.

It is thus seen that I have provided a method of preparing camera copy of the type described in my Patent No. 2,355,884, but in which I have eliminated the step of forming one series of dots, and have also eliminated other steps entailing labor and expense.

It is to be understood that various changes may be made in the details of the method and medium without departing from the spirit and scope of the invention.

Having thus described my invention, I claim:

1. In a method of preparing a medium for use in making camera copy, the steps which consist in applying to a non-moisture-proof surface, a solution containing at least two ingredients, one of which remains superficially on said surface as a chemically-developable pattern comprising uniformly spaced dots, and the other of which impregnates said surface and spreads uniformly in all directions to form a second pattern comprising spaced dots larger than said first-named dots and in registration with said first-named dots, the ingredient forming the first-named dots being mercurous chloride, and the ingredient forming the larger dots being cobaltous chloride.

2. A method, as defined in claim 1, in which the cobaltous chloride dots are subjected to treatment which converts them to insoluble cobaltous tungstate, and the mercurous chloride dots are insolubilized by treatment with a chemical containing formaldehyde.

3. A method, as defined in claim 2, in which the insolubilized mercurous chloride, is developable by means of thiourea, and the cobaltous tungstate dots and mercurous chloride dots are simultaneously developable by means of sodium sulphide.

4. A medium for use in preparing camera copy, said medium consisting of a surface having chemically-developable patterns, one of said patterns consisting of uniformly spaced dots of one' substance disposed below said surface, and the other of said patterns consisting of uniformly spaced dots of another substance smaller than said first-named dots and superimposed upon the latter, and disposed above said surface, the dots below the surface containing cobaltous tungstate and the dots above said surface containing mercurous chloride.

MAURICE D. McINTOSH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 20,503 McIntosh Sept. 14, 1937 2,355,884 McIntosh Aug. 15, 1944

Claims (1)

1. IN A METHOD OF PREPARING A MEDIUM FOR USE IN MAKING CAMERA COPY, THE STEPS WHICH CONSISTS IN APPLYING TO A NON-MOISTURE-PROOF SURFACE, A SOLUTION CONTAINING AT LEAST TWO INGREDIENTS, ONE OF WHICH REMAINS SUPERFICIALLY ON SAID SURFACE AS A CHEMICALLY-DEVELOPABLE PATTERN COMPRISING UNIFORMLY SPACED DOTS, AND THE OTHER OF WHICH IMPREGNATES SAID SURFACE AND SPREADS UNIFORMLY IN ALL DIRECTIONS TO FORM A SECOND PATTERN COMPRISING SPACED DOTS LARGER THAN SAID FIRST-NAMED DOTS AND IN REGISTRATION WITH SAID FIRST-NAMED DOTS, THE INGREDIENT FORMING THE FIRST-NAMED DOTS BEING MERCUROUS CHLORIDE, AND THE INGREDIENTS FORMING THE LARGER DOTS BEING COBALTOUS CHLORIDE.

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