Fig. 15.—Register marks (section of).

In section the two register marks would be as above.

The register marks must be smoothly and evenly cut so that the paper, in printing, may slide easily home to its exact place.

When the design of the key-block and the two register marks have been cut and cleared, the trace of paper and paste on the uncut parts of the wood should be carefully washed off with a piece of sponge and warm water. The block is then finished and ready for use. The key-block, however, is only one of the set of blocks required for a print in colour, but the colour blocks are simpler and require, as a rule, far less labour.

The colour blocks are planned and established by means of impressions taken from the key-block. For this purpose the register marks are inked[2] for printing as well as the design on the block, and the impressions must include both. These impressions are taken on thin Japanese paper, but not necessarily the thinnest tissue. If the thinnest is used, it should be pasted at the corners to a sheet of stiffer paper for convenience in handling.

It is then a fairly simple matter to take one of these key-block impressions and to make a plan of the various colour-blocks that will be required. These should obviously be as few as possible.

It is not necessary to provide an entire block for each patch of colour, but only the extent of surface required for each coloured portion of the print, as well as for its pair of register marks. Patches of different colour that are not adjacent to one another on the design of the print may be cut on the same block, provided they are not too close for free colouring of the block in printing. Each block also may be cut on both sides, so that there is considerable scope for economy in the arranging and planning of the colour blocks.

When the arrangement of the plan of colour has been simplified as far as possible, a new block is prepared as described above, and a sheet of thin Japanese paper (unsized) is cut large enough to cover the print design and its register marks. The clean surface of the new block is covered thinly with starch paste well rubbed into the grain, and while this is still wet an impression on the sheet of thin Japanese paper is taken of the entire key-block, including its register marks in black, and laid before it is dry face downward on the pasted surface of the new block. This should be done as already described on page 25. It should be rubbed flat with the printing pad and left to dry.

This operation requires careful handling, but it should be done easily and methodically, without any hurry.

Each side of the set of colour planks should be treated in the same way—a thin impression of the key-block and its register marks being laid upon each. It is advisable to paste down a freshly taken impression, each time, while the ink is still moist, for if these are allowed to dry, the shrinking of the paper causes errors of register.

When these new blocks are dry, the patch of colour to be cut on each surface should be clearly indicated by a thin wash of diluted ink or colour, but not so as to hide the printed key line.

The blocks may then be cut. A V-shaped cut is made round each form, as in the case of the key-block, and the clearing proceeds in the same way, but it is only necessary to clear a space of about an inch round each form: the rest of the wood should be left standing. A section of the printing surface of a colour block would be as follows: