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October 15, 2015

Chapter Three [The Technique of the Color Woodcut]


PIGMENT

Buy only colors of proved permanence, in powder form —not necessarily finely ground, but dry.

Mr. Howell C. Brown, of California, and his brother have done good work in testing various makes of pigments. Some results of their labor are recorded in the Original Color Print Magazine for 1925. They have established the reputation of one color at least —Cadmium Red —which is a notable addition to the modern palette.

Luminosity is a quality dependent as much on technique as on the physical properties of individual pigments. When you are experienced in prints you will notice that, held to or against the light at a particular angle, the richness of printed color is very much enhanced. Mr. Giles has written of this phenomenon, which he calls dichroism, borrowing the term from mineralogy.

Opaque and transparent pigments must be differentiated, both as regards design and over-printing. Opaque colors printed over others often are effective. The addition of white to give body and opacity to transparent pigment is justified on occasion. Mr. Urushibara has a print in which slim grasses and flowers with hovering butterflies are overprinted on a ground of solid black. Some artists justly question the propriety of using colors which change in artificial light, regarding the fact that pictures are more often viewed thereby than by daylight. Blue, for example, unless with a greenish bias, loses most of its quality.

Some colors print very easily and smoothly, but others sometimes need the addition of glue or gum to ease their transference from wood to paper. The color is ground in water, conveniently on a ground glass slab with a muller.


MEDIUM

The medium or binder is paste, made with starch, flour or rice. The first is most easily made, but its adhesive properties are apt to injure the surface of the paper if too much is used. Rice paste does no harm in that way.

To make starch paste, mix dry starch with enough cold water to make a stiff cream. (A teaspoonful of starch makes a cup of paste). Add boiling water, stirring the while, until the liquid thickens. If it does not thicken, boil it.

For printing add water after the thickening occurs, until you have a liquid of the consistency of milk, because further coagulation takes place when the paste cools. Rice flour or powder should always be boiled with water.

Gum arabic may be used as a binder, with glycerine or paste, for special purposes, where, perhaps, a little more intensity of color is desired.

An intense black may be obtained by grinding the crude pigment in warm glue size. This is the Tsuya-Zumi of the Japanese. According to Mr. E. F. Strange the glue-water medium used was made in the proportion of about one-third of an ounce of glue to three-fourths of a pint of water, in which a little alum had been dissolved. This mixture coagulates of course unless it is warmed, and may be kept some time in that condition without deterioration. While in use the vessel containing it should be kept standing in a pan of hot water.


BRUSHES

A variety of brushes are suitable for spreading color over the blocks. An inch hog-hair brush, such as is used for oil-painting, is adequate for smaller areas, but a wider and thicker brush is better. Probably the best is the badger brush made especially for this purpose by the Bryce-Smith Company of London. An inch brush of that type is an inch long in the bristle and three-quarters of an inch thick.

Cut up newspaper two inches larger all round than the printing paper. Dampen them evenly with a brush, but not so much as to show a watery sheen on the surface. On each sheet lay a piece of printing paper, right side down (always stack your printing sheets in this way), and leave the pile to stand with a board on top for, say, one hour. A sheet of zinc or glass is really preferable to a board, which very soon warps under this treatment.

Take out the damp news-sheets, and distribute them between top and bottom of the pile. In a humid atmosphere one or two sheets only are necessary; the rest may be removed altogether. Leave for at least one hour and a half. Damp paper will not mildew for three days at any rate. The most convenient time for damping is the evening previous to the day of printing; the papers may remain piled safely all night.

Japanese printers dip the printing sheets in water and hang them up to drain. The time allowed for drainage is about twenty minutes, but it depends obviously on the state of the atmosphere. Blotting paper may be used for absorbing superfluous moisture.

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