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
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.

Fresh ink may at any time be obtained rapidly in small quantities by rubbing down a stick of Chinese ink on a slab in the ordinary way, but this is very laborious, and is only worth while if one needs a small quantity of a glossy black, for which the rubbed-down ink containing all its glue is the best.