US1190487A - Art of photo-engraving. - Google Patents

Description

H. J. VAN VALKENBURG ART OF PHOTO ENGRAVING.

APPLICATION FILED JUNE 9, 1915.

Patented July 11, 1916.

' INVENTOR Harry J I n 1611M my 6 By WITNESSES.

HARRY J. VAN VALKENBUBG, OF ROCHESTER, NEW YORK.

ART OF PHOTO-ENGBA'VING.

Specification of Letters Intent.

Patented July 11, 1916.

Application filed June 9, 1915. Serial No. 33,167.

To all whom it 111 (13 concern:

Be it known that I, HARRY J. VAN VALK- ENBURG, a citizen of the United States, residing at Rochester, in the county of Monroe and State of New York, have invented a new and useful Improvement in the Art of Photo-Engraving, of which the following is a specification.

, My invention relates more particularly to hoto-engraving in half-tone, and the obect thereof is, by means of photography, to drop out or eliminate all half-tone dots from any predetermined portions on a negative made through any half-tone screen whether ruled or grained.

Heretofore, in order to have high light or pure white background, free from all half-tone dots, it has been necessary after the reproduction had' been transferred to the zinc or copper plate to follow the outline of the photograph with a ,sharp tool called a graver in order to remove the half-tone dots adjacent thereto before usin mainder of the background are routed out. This first named operation not only requires a skilled hand but is slow and consequently expensive, while in the practice of my invention the necessity of such operation is entirely obviated.

The method and means I employ in eliminating half-tone dots from any predetermined portions on a negative, as around the outline of. the object photographed, areillustrated, diagrammatically, in the accompanying drawings, in which,

Figure 1 shows a face view of a copy (photograph, drawing, print, lithograph or other subject) of which a half-tone negative is to be made; Fig. 2, a view of the copy similar to Fig. 1 but showing a sheet of thin colorless transparent material secured to the face thereof on which is made a tracing, in white opaque pigment, over that portion of the copy from which all half-tone dots are to be eliminated on the negative; Fig. 3, a side view of the parts seen in Fig. 2; Fig. 4, a View showing a portion of a sheet of colored transparent material that may be used instead of that shown in Fig. 2; Fig. 5, a view similar to Fig. 2 but showing a backing sheet disposed between the transparent material and the copy, such sheet being of a color having non-actinic value; Fig. 6, a side View of the parts seen in Fig. 5 placed in a copy holding frame with the back and glass front of such frame shown in vertical the inst-rument by means of which the ots in the re section; Fig. 7, the appearance of a negative if developed after an exposure had been made with the backing sheet in the position shown in Fig. 5; Fig. 8, a face view of a half-tone negative on which a photograph of the copy has been made; Fig. 9, a face view of a half-tone plate made from the negative seen in Fig. 8; and Fig. 10, a view similar to Fig. 2 but showing a reversal of theprocess, as will be explained.

Similar reference characters refer to similar parts throughout the several views.

In Fig. 1 the numeral 1 represents the copy to .be photographed which of itself may be a photograph, print, drawing, lithograph or othensubject, and at 2 is seen the background from' which on the finished print all half-tone dots are to be eliminated.

A sheet of thin colorless transparent material 3, preferably celluloid about 3/1000 of an inch thick and of sufficient area to cover the entire surface to be photographed, 1s placed over the copy 1 and attached firmly thereto at two or more points by means of a suitable adhesive or, if desired, may be covered over its entire surface with a transparent cement in order to be held in close contact with the copy. Upon this transparent material a tracking 4 is then made in opaque pigment of high actinic value, as white, of that portion of the copy from which all dots are to be eliminated by photography from the half-tone. That portion of'the negative on which no dots are to appear, as illustrated in the drawings, is a margin following the outline of the object 5 on the copy 1.

After the tracing 4 has been made the sheet 3 is raised from the copy 1 to permit the insertion therebetween of a backing 6 of suitable material, as celluloid, paper or other substance of a color having a non-actinic value, but is held fast to the copy at two or more points in order that the tracing may again be brought into registration with the object 5. The material 6 indicated in Figs. 5 and 6 of the drawings, and which I prefer to use, is red celluloid. All three, copy, tracing and backing are next placed in the usual copy holding frame 7 having a hinged glass front 8, sufficient pressure being) brought to bear to hold such three mem ers in perfect contact wit-h each other, and in order that the frame may be opened to later remove the backing 6 without disturbing the position of the copy 1 such copy is secured by tacks, not shown, to the back of the frame 7. A photographic exposure This exposure may be made either with or without the use of a half-tone screen, but if made through the screen sufiicient exposure must be given together with aproper relative lens aperture and screen separation to insure the complete closing up of. all halftone dot formation. If the'negative were developed at this time in the process the result would be as shown in Fig. 7 in which 9 represents the photograph of the tracing 4, the remainder of the negative 10 being clear glass.

After such first exposure is made, which may be almost instantaneous or var up to forty-five seconds or more, the hacking member 6 is removed on opening the glass front 8 of the copy holder and which is thereafter again closed to hold the transparent sheet 3 and copyl in contact with each other and with the tracing 4 in perfect registration with the object 5. The regular half-tone exposure of the copy 1 is then made and the developed negative 11 would 7 appear as in Fig. 8 with the object 5 and background 2 shown in half-tone dots, but with the margin 9 formed around the outline of the object showing black on the negative.

A half-tone plate made from the negative 11 would be as indicated at 12 in Fig. 9, and it will readily be seen that with the margin around the outline of the object photographed free from all half-tone dots the use of the graver tool, for the purpose above referred to, is dispensed with and that the remainder of the background may be cleared of half-tone dots by use of the routing instrument only.

If desired, the transparent sheet 3 having the tracing 4 thereon may be removed with the backing 6 from the copy 1 before the second exposure or half-tone negative, proper, is made; and it will, therefore, be readily understood that, if a tracing 4 in pigment of high actinic value is made on a sheet of transparent material, as indicated in Fig. 4 at 13, of a color having non-actinic value, the backing sheet 6 need not be used.

The entire process of making the half- 7 tone negative'may be reversed by using,

instead of a pigment of high actinic value and making a tracing of that portion of the copy from which all half-tone dots are to be eliminated,a pigment of non-actinic value and making a tracing of that portion of the copy from which such dots are not to be eliminated in the half-tone negative, a tracing of this kind being shown at 14 in Fig.

10 as made on a sheet of transparent material 3 similar to that shown in Fig. 2; and

when this reverse method is followed an opaque backing sheet 15 having high actinic value is used, and both the backing and the sheet 3 on which the tracing is made must be removed from the copy before the second exposure of the negative is made.

It is believed that, from the foregoing description, the method of and means used in practising my invention, as well as the purpose thereof, are sufliciently understood to call for no further explanation herein.

What I claim is:

1. The improvement in the art of photoengraving which consists in eliminating half-tone dots from predetermined portions of a half-tone negative by covering the copy to be photographed with a trans arent material including a layer of a co or having non-actinic value, tracing on said material over portions of said copy from which all half-tone dots are to be eliminated from the negative with a pigment having high actinic value, photographing said tracing on a sensitized plate, removin said non-actinic covering, and photographlng said copy by a second exposure of the same plate through a half-tone screen.

2. The improvement in the art of photoengraving which consists in eliminating half-tone dots from predetermined portions of a half-tone negative by covering the surface of the copy to be photographed with a transparent material. tracing on said cover overportions of said copy from which all half-tone dots are to be eliminated from the negative with a pigment having high actinic value, inserting a backing of a color having non-actinic value between said copy and said cover. photographing. said tracin on a sensitized plate, removing said backlng, and photographing said copy by a second exposure of the same plate through a halftoned screen.

3. The improvement in the art of photoengraving which consists in eliminating half-tone dots from predetermined portions of a half-tone negative by covering the surface of the copy to be photographed with a transparent material, tracing on said cover with a pigment over certain portions of said copy, inserting an opaque backing sheet between said copy and said cover, photographing said tracing on a sensitized plate, removing both backing and cover, and photographing said copy by a second exposure of the same plate through a half-tone screen, said backingpreventing the photographing of the copy during said first exposure.

HARRY J. VAN VALKENBURG.

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