The McCorquodale-Gresham Process for Colour Photogravure

Abstract

In the conventional photogravure process, printing is carried out from etched cylinders in which the printing areas are recessed below the surface. The image is separated into small cells which vary in depth, in accordance with the tone value to be printed, but have substantially constant area throughout the tone range. There are definite advantages in using a system in which both the depth and area of the printing cells are varied and, as an example of this, the Dultgen process is described. A further advance has been made in the McCorquodale-Gresham process where a screen positive of special characteristics is made from a finished continuous tone positive by reversal processing. Both the continuous tone and the screen positive are then used to produce a printing cylinder.