US1273993A

US1273993A - Printing-plate for multicolor photo-engraving.

Info

Publication number: US1273993A
Application number: US87555014A
Authority: US
Inventors: Carl Blecher
Original assignee: ROTOPHOT AKT GES fur GRAPHISCHE IND
Current assignee: ROTOPHOT AKT GES fur GRAPHISCHE INDUSTRIE; ROTOPHOT AKT GES fur GRAPHISCHE IND
Priority date: 1914-12-04
Filing date: 1914-12-04
Publication date: 1918-07-30
Anticipated expiration: 1935-07-30

Description

or ED STA NT- FFE CARL BLECHEB, or BERLIN-DAHLEM, GERMANY, Assrcrnon To ROTOPHOT Am,

m ommscnr: mnusrnm, or BERLIN, ennmanm- PRINTING-PLATE FOR MULTICOLOR PHOTO-ENGRAVIlVG.

No Drawing.

To all whom it may concern:

Be it known that CARL BLECHER, a subj ect of the Kin of Prussia, residing at Berlin-Dahlem, ermany, F riedbergstrasse 23, has invented certain new and useful Improvements in Printing-Plates for Multicolor Photo-Engraving, of which the followin is a specification. I

l y invention relates to printin plates for printing threeor multicolor p oto-engravings on printing machines, and the ob- ]ect of my invention is to provide printing plates screened in such a manner as to render the covering of any part of the printing surface corresponding to any represented tone, for the purpose of fine etching any portion thereof safe and easy.

The single printing plates for threeor multicolor photo-engravings for printing machines are commonly prepared in the same way as ordinary one-color printing plates. Before or after the transparent half-tone positive separated into the difierent colors is printed on pigment-paper, a cross-lined screen showin black dots and white crossed lines is rinted upon the same paper, and the screened half-tone print so obtained is then transferred to the plate or cylinder. After thorough etching the print appears upon the metal covered throughout with the same cross lines as compared with the surface of the plate or cylinder, the gradation between these 1ines bein merely formed by their different depth. n looking at the surface of a plate or cylinder prepared according to this method it is extremely diflicult for the eye to trace the demarcation of thedifierent tones, as it is almost impossible to distinguish differences in tone by aid of the minute differences in depth. Under these circumstances it is almost impossible to effect the proper covering of the area of the printing surface correspondin to certain tones as is necessary to provide for the fine etchin of the areas corresponding to other tones and which are not covered.

According to the present invention this difficulty is fully dealt with and the covering of the necessary surface indispensable to Specification of Letters Patent. t t J ly 30, 191

Application filed December 4, 1914. Serial No. 875,550.

produce fine etching of a part or parts of the single printing plates is rendered easy by producing different screen effects for each of the single tones. screens may differ either in number; or in form, size and arrangement, it being merely necessary to employ screens suitable for the particular shade of the tone and for the mixed-color type in question. The kindof screen to be employed in each case is unim v portant.

There are numerous methods available for producing such a varying screening. A ve simple and eflective method is the following; A piece of tracing paper of sufficient size is placed over the transparent positive and the screening to be obtained within the different tones is produced on the paper by means of an agate stylus and a number of differently grained gelatin films. The screens produced in this manner are then covered with bronze to insure better covering. V

The transparent positive and the piece of tracing paper carrying the different screens should be provided with accurately coinci-.

dent cross-marks. The transparent positive is then printed upon the pigment paper, it being essential that the cross marks are plainly visible on the paper. The tracing paper carrying the screens is then placed in the printing frame, the pigment paper print is adjusted thereon by means of the cross marks and the screens are then printed upon the paper. In the prints as well as in the transfers the different tones will now easily be distinguished by means of the difference in division. If the transfer is thoroughly etched and if it'is then desired to subject the plate 01- cylinder, after a proof has been taken and the surface hasbeen inked in.

order to protect the projecting parts, to a further treatment by fine etching, it is a matter of the greatest facility to cover or leave free the right parts, the different tones being strongly contrasted through the dif ference in screening.

I claim 1. A printing plate for use in three or GES.

The elements of the multicolor hoto-engraving printing having eral tones in a print distinguished from one 1 the areas t ereof requiring etching to difanother by dots and lines arranged in different depths to produce the several tones in ferent relations.

a print distinguished from one another In testimony whereof I afliX my signature by the representation thereon of different in presence of two Witnesses.

screens. CARL BLECHER.

2. A printing plate for use in three or Witnesses:

multicolor photosengraving printing having WOLDEMAR 'HAUPT,

the areas thereof corresponding to the sev- HENRY HAsPnR.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents. Washington, ILG.