"Light and shade" reproductions are more difficult. It is obvious that black ink applied all over a printing surface cannot print the innumerable grey tints which make up the light and shade of a picture; it can only print solid black. What can be done is to give effect to tints by printing masses of black through which the white paper is allowed to appear in varying proportions. This was accomplished by the old wood engravers by the use of white lines produced by cutting away portions of the surface of a solid block of wood. In the modern photo-process a negative is made through a ruled screen on glass, and in the photographing this screen breaks up the tints of the original into dots of such a size and such a distance from each other as to give the effect, when printed, of tints of the depth required. The method really depends on an illusion. In any one screen the dots are equally spaced but of different sizes, and each dot carries an amount of ink proportionate to its size; so that the light tones are represented by very small dots, while larger and larger dots, up to a solid black, give the darker tones.

The fineness of the screen ruling varies from 50 lines to the inch to 200 lines, the commoner screens having 80, 100, 133, or 150 lines. Much depends on the paper to be used for printing, the finer screens requiring a smooth-coated paper.

The three-colour process is the modern method of colour reproduction. The coloured original is first photographed three times, each time with a different coloured glass or film, called a colour filter, placed between the lens and the plate. The effect is to divide the colours of the original photographically into three main divisions one being the portion of the picture which is yellow, or has yellow in its composition; the second, which is red, or has red in it; and the third which is blue, or has blue in its make-up. Almost any range of colours can be reproduced and

1 It is possible to reproduce by the line process a drawing on a coloured ground provided there is a strong contrast between the tinted ground and the drawing. In such cases the photographic methods have to be modified which considerably increases the cost.

printed on a good white paper by the use, in proper and varying proportions, of yellow, red, and blue inks. A plate is made with each of the different filters, and then these are printed one over the other, the usual order being first yellow, then red, and lastly blue. Bright water-colour sketches without too much fine detail are most readily reproduced, and are also more satisfactory because the three-colour print does not differ much from the original.

Fashion Drawing Sections

Part-1 Part-2 Part-3 Part-4 Part-5 Part-6 Part-7 Part-8