The number of prints to be attempted at one printing will vary with the kind of work and with the printer's experience. The printing may be continued during three days, but if the paper is kept damp longer, there is danger of mould and spotting. With work requiring delicate gradation of colour and many separate block impressions twenty or thirty sheets will be found sufficient for three days' hard work. The professional printers of Japan, however, print batches of two hundred and three hundred prints at a time, but in that case the work must become largely mechanical.[4]
The batch of paper and damping sheets should remain between the boards for at least half an hour when new sheets are being damped for the first time. The damping sheets, all but the top and bottom ones, should then be removed and the printing sheets left together between the boards for some time before printing. An hour improves their condition very much, the moisture spreading equally throughout the batch of sheets. Before printing they should be quite flat and soft, but scarcely moist to the touch. If the sheets are new, they may even be left standing all night after the first damping, and will be in perfect condition for printing in the morning without further damping. No weight should be placed on the boards.
Although no paper has hitherto been found that will take so perfect an impression from colour-blocks as the long-fibred Japanese paper, yet it should be the aim of all craftsmen to become independent of foreign materials as far as possible. There is no doubt that our paper-makers should be able to produce a paper of good quality sufficiently absorbent to take colour from the wet block and yet tough enough to bear handling when slightly damp.
If a short-fibred paper is made without size, it comes to pieces when it is damped for printing. But the amount of absorbency required is not so great as to preclude the use of size altogether. It is a problem which our paper-makers could surely solve. A soft, slightly absorbent, white paper is required. At present nothing has been produced to take the place of the long mulberry fibre of the Japanese, which prints perfectly, but it is far from being pure white in colour. A white paper would have a great advantage in printing high and delicate colour schemes.
INK
Next in importance is the preparation of the ink for printing the key-block or any black or grey parts of a design. As a rule the key-block is printed black, more or less diluted with paste; indeed the key-block is often printed very faintly by means of paste only just tinged with a trace of black.
Fig. 18.
Cork of ink-bottle with wad for preservative.
The use of colour for the key-block is treated in Chapter VII. The ink is prepared as follows. Take a stick of solid Chinese ink of good quality, and break it with a hammer into fragments; put these to soak in a pot with water for three or four days. (The quality of the sticks of Chinese ink varies greatly. The cheap sticks make a coarse and gritty ink which does not print well.) Day by day pour off the water, adding fresh, so that the glue that soaks out of the softened black fragments is removed. Three days is usually long enough for this. If left too long the whole mass goes bad and is spoiled. When the black mass is soft and clean drain off the water and rub the ink smooth in a dish with a bone palette knife. It is then ready for use, but would rapidly go bad if not used up at once, so that a preservative is necessary to keep a stock of ink in good condition. An effective method is to put the ink at once into a well-corked, wide-mouthed bottle. To the under side of the cork is nailed a little wad of unsized paper soaked with creosote. By this means ink can be kept in perfect condition for weeks or months. A drop of fresh creosote should occasionally be put on the wad fixed to the cork.