The tools required for blocking are "blocks" or "stamps," composed of very small pieces, or in one block cut to the size of the book. In any case, the block has to be fastened to the movable plate at the bottom of the heating box of the blocking press. To block the sides of a book, glue a stout piece of paper upon the movable plate. Then set the blocks upon one side of the book in exact position, and place that side upon the bed of the blocking press, leaving the volume hanging down in front of the press. The bed is next fixed, so that the centre of the board is exactly under and in the centre of the heating box. When quite true, the sides and back gauges are fixed by screws. Pull the lever so that a slight pressure upon the plate be given; release the press and take out the book and examine if all be correct. Some of the blocks may re-quire a small piece of paper as a pad, so as to increase the pressure, others to be shifted a little. Now glue the back of the stamps and replace them. Put the whole under the top plate in the press, heat the box, and pull the lever over; let the book remain for some little time to set the glue. Take out the book, examine if perfectly square and correct, but replace it with a soft millboard under the stamps and pull down the press.
The lever must remain over and the blocks be under pressure until the glue is hardened.
Another method is to glue upon the plate a piece of thick paper, and mark upon it the exact size of the book to be blocked. Strike the size from the centre, and from that draw any other lines that may assist in placing the blocks. Arrange the blocks upon the plate so as to form the design; when correct, paste the blocks on their backs and replace them on the plate. When the paste adheres a little, turn the plate over and put it into the press. Apply heat to the box; pull the lever over; and when the paste is set, regulate the bed and gauges.
When the press is properly heated, throw back the lever: take out the millboard from under the stamp, and regulate the degree of pressure required by the side screw under the bed. Place upon the bed the side to be stamped, hold it firmly against the guides with the left hand, and with the right draw the lever quickly to the front. This straightens the toggels and forces down the heating box, causing a sharp impression of the stamp upon the leather or other material. Throw or let the lever go back sharply and take out the book. If the block be of such a design that it must not be inverted, the whole of the covers must be blocked on one side first, and the block turned round for the other side, or the design will be upside down.
Work for blocking in gold does not require so much body or preparation as if it were gilt by hand. Morocco can be worked by merely washing the whole surface with a little urine or weak ammonia; but it is safer to use a coat of glaire and water, mixed in proportions of 1 to 3. The heat should be moderate and the working slow.
Calf should have a coat of milk and water or thin paste-water as a ground, and when dry another of glaire, both laid on evenly; but if only portions are to be gilt, such as a centre-piece, and the rest dead, the centre-piece or other design should be pencilled in with great care. The design is first slightly blocked in blind as a guide for the glairing. The edge of the glaire always leaves a dark stain. The heat required for calf is greater than for morocco, and the working must be done more quickly.