A set of blocks consists of a key-block and several colour blocks. The block that must be cut first is that which prints the line or "key" of the design. By means of impressions from this key-block the various other blocks for printing the coloured portions of the design are cut. The key-block is the most important of the set of blocks and contains the essential part of the design.

A drawing of that part of the design which is to be cut on the key-block should first be made. This is done on the thinnest of Japanese tissue paper in black indelible ink. The drawing is then pasted face downward on the prepared first block with good starch paste. It is best to lay the drawing flat on its back upon a pad of a few sheets of paper of about the same size, and to rub the paste on the surface of the block, not on the paper. The block is now laid down firmly with its pasted side on the drawing, which at once adheres to the block. Next turn the block over and lay a dry sheet of paper over the damp drawing so as to protect it, and with the baren, or printing rubber, rub the drawing flat, and well on to the block all over.

The drawing should then be allowed to dry thoroughly on the block.

With regard to the design of the key block, it is a common mistake to treat this as a drawing only of outlines of the forms of the print. Much modern so-called decorative printing has been weak in this respect. A flat, characterless line, with no more expression than a bent gaspipe, is often printed round the forms of a design, followed by printings of flat colour, the whole resulting in a travesty of "flat" decorative treatment.

The key design should be a skeleton of all the forms of a print, expressing much more than mere exterior boundaries. It may so suggest form that although the colour be printed by a flat tint the result is not flat. When one is unconscious of any flatness in the final effect, though the result is obtained by flat printing, then the proper use of flat treatment has been made. The affectation of flatness in inferior colour printing and poster work is due to a misapprehension of the true principle of flat treatment.

Plate V. Impression (Nearly Actual Size) Of A Portion Of A Japanese Wood Block Showing Great Variety In The Character Of The Lines And Spots Suggesting Form

As an illustration of the great variety of form that may be expressed by the key-block, a reproduction is given (page 33) of an impression from a Japanese key-block. It will be seen that the lines and spots express much more than boundaries of form. In the case of the lighter tree foliage the boundaries are left to be determined entirely by the subsequent colour blocks, and only the interior form or character of the foliage is suggested. The quality or kind of line, too, varies with the thing expressed, whether tree, rock, sea, or the little ship. The design, too, is in itself beautiful and gives the essential form of the entire print.

The study of the drawing of any of the key-blocks of the Japanese masters will reveal their wonderful power and resource in the suggestion of essential form by black lines, spots, and masses of one uniform tint of black or grey. The development of this kind of expressive drawing is most important to the designer of printed decoration, whether by wood blocks, or lithography, or any other printing process.

Other good types of drawing for the purposes of key-blocks in wood are given on Plate V facing page 26 and Plate XVI p. 110 in Appendix.

When the key-block with its design pasted upon it is thoroughly dry, a little sweet oil should be rubbed with the finger at that part where the cutting is to begin, so as to make the paper transparent and the black line quite clear.

In order to keep the block from moving on the work-table, there should be fixed one or two strips of wood screwed down, to act as stops in case the block tends to slip, but the block should lie freely on the table, so that it may be easily turned round during the cutting when necessary. One should, however, learn to use the cutting knife in all directions, and to move the block as little as possible.

The knife is held and guided by the right hand, but is pushed along by the middle finger of the left hand placed at the back of the blade, close down near the point. The left hand should be generally flat on the work-table, palm down, and the nail of the middle finger must be kept short. This position is shown (fig. 7) on p. 30.

The flat side of the knife should always be against the line to be cut.

Sometimes it is convenient to drive the knife from right to left, but in this case the pressure is given by the right hand, and the left middle finger is used to check and steady the knife, the finger being pressed against the knife just above the cutting edge.