"A true half tone will be best obtained by not relying entirely on the mechanical means, but assisting them with some hand work, either in the shape of re-etching or engraving, or both."
The application of hand engraving to photo-mechanical work has been chiefly due to American process workers, who applied the technique of the wood engraver's art to the amplification of their half tone blocks.
Tri-chromatography.—The "Three Colour Process" is more or less an application of half tone engraving to chromo-typography. The colours, each in their relative value, are produced by purely photo-mechanical methods—the colours of the original copy being dissected by means of specially prepared colour screens. Half tone blocks are made from each of the three negatives, and superimposed in accurate register in the subsequent printing, when, of course, the primary colours, red, blue, and yellow, are used.
The process possesses brilliant and effective illustrative power, offers ample scope for the ingenuity and manipulative skill of artist, engraver, and printer, and promises well-nigh unlimited possibilities as a medium of pictorial expression.
(c) Photogravure.—Photogravure may be very briefly described. It is a photo-mechanical process, in which rich, soft tones of surpassing delicacy and undeniably artistic effect are striking peculiarities. Unlike "line" and "half tone" engraving, it is an intaglio process, in which the printer as well as
the etcher must possess a profound artistic perception.
Reproduction by R. J. EVERETT & SONS' "INK-PHOTO" Process.