The following extract is taken from Hillier J., Japanese colour prints., Phaidon, 3rd edn 2nd impression, 1991
The colour-print was the result of the collaboration of four distinct people:
the publisher, who commissioned the work and co-ordinated the operations of
the other three concerned in its production, and whose importance, consequently,
cannot be over-rated - many of the finest prints are due to the enterprise and
discernment of publishers like Tsutaya Jusaburo and Eijudo; the designer, the
engraver; and the printer. To these, some would add a fifth, quite logically
- the paper-maker: the superb texture and surface of the hand-made, mulberry-bark
papers do much to enhance the bloom and soft radiance of the colours.
The woodcut medium came naturally to the Ukiyo-e artists. There was already in existence a body of facsimile wood-engravers, long trained in the cutting of brush-drawn characters for the texts of books. To such engravers, the cutting of an outline block from a brush drawing supplied by the artist was a comparatively simple matter, and an extremely high standard of fidelity was normal. It is a matter of surprise that the application of colour by wood-blocks was so long deferred, for Chinese colour-prints of the seventeenth century, employing a wide range of colours, must have been known in Edo. No doubt the need to keep the price within the reach of the humble Edo folk was one of the factors responsible.
A great deal depended on the craftsmen responsible for block-cutting and printing. The artist merely supplied the drawing on transparent paper and indicated the colours by painting them in on a 'pull' from the 'key-block', as the outline print was known. The engraver, pasting the drawing face-down on a block of hard wood like cherry (not on the 'end-grain' as has been customary in the West since Bewick's day, but on the 'plank' in the manner of Diirer's engravers), cut around the lines with a knife, and by clearing the wood between the lines, left them in high relief. The ink having been rubbed on to the raised lines, proofing paper was placed over the block, pressure was applied by rubbing a twist of hemp over the back of the paper, and a proof of the engraver's facsimile of the artist's design thus secured.
Usually, the artist's original drawing was cut to pieces by the engraver in preparing the key-block, but a number of brush drawings for prints exist which seem to suggest that in some cases the engraving was made from a copy of the original design.
After the artist had indicated the colours on a proof of the key-block, a separate block had to be cut for each colour that was to be printed, and in a print of complex tints, as many as ten or more such additional blocks might be required, from which, with over-printings, a remarkable range of colour was obtainable. The colours were mixed by the printer on each block separately, a little size made from rice being added to give a firm consistency. Accuracy or register, of first importance as a print passed from one block to another to receive its succession of colours, was secured by a guide mark for the proofer, consisting of a right-angle cut at one corner of each block and a straight line at an adjoining side, aligned with one side of the right-angle.
Until the nineteenth century, the colours were mainly of vegetable origin, and, unfortunately, fugitive on exposure to light, the sky-blue, violet and pink fading to buffs and greys still beautiful in themselves, but something quite different from the bright hues that originally caught the eye of the Edo purchaser. With the singular perversity of their race, some collectors have affected to admire the time-faded print in preference to another in its original colours, but although many fade in harmony, the quiet, subdued tones of such prints are those of preserved flowers, lacking the gaiety and liveliness of the living thing. Besides, quite often the precious harmony of colour achieved by some artists, Harunobu in particular, is destroyed when more stable greens, yellows and a chocolate brown remain unimpaired whilst other shades have become uniformly dulled. To collectors of the kind mentioned, the print in its original state comes as much of a shock as cleaned pictures, seen at last in all their bright colour, come to lovers of the 'embrowned' tones of the Old Masters.
Among the various embellishing devices used by the printer are the use of mica in backgrounds, or for picking out mirrors and frosty or icy surfaces; the application of metal-dusts, either sprinkled or applied by block; and gauffrage, or blind printing, for indicating the patterns and folds of dresses, the plumage of birds or the fur of animals, by lines in relief but without colour.
There seems to be no certainty as to the number of prints taken from one set of blocks, but an extant letter of Hokusai's to one of his publishers set the limit at 200 prints. After long use, a saturated block ceases to take colour evenly and the fine lines begin to wear down, but modern block-makers concerned with producing facsimiles of old prints, take many more proofs than 200 from a block, and one publisher has expressed the view that a thousand or more can be taken before the block deteriorates.
More information on the processes can be found at the Tokugawa Gallery site and an excellent illustration of the individual blocks in a modern print can be found at John Fiorillo's site.