Fig. 79—Specimen of tooling done in the Düsseldorf Technical School.
Near the finishing stove should stand—as also for blind tooling—a shallow saucer containing water and also a common brush similar to those sold with bottles of gum. A drop of water is thrown from this brush on to the hot tool in order to test its heat. Cloth is printed with fairly hot tools; they should hiss a little when tested. Goat-skin requires a heat almost sufficient to produce hissing, whilst hissing would indicate too hot a tool for use on morocco, and all sheep-skins will bear only moderate heat. If the roll was too hot, the gold would have no brilliance, and if too cold, would appear broken. Calf requires the same heat as cloth, but quick working, especially on first applying the tool. The roll has a long handle which rests against the shoulder whilst held in the right hand. When getting into position for an impression the thumb-nail of the left hand is used as a guide and support.
Fig. 80—Leather binding by Oswald Kob, Bozen.
A line around a cover is marked out correctly with dividers and folder, picked out with size, and printed in gold in the same way. The rolls have a notch, which is for starting and ending at the corners; these must always be joined exactly. Rolls for two or more lines must print the corners perfectly diagonal, and for this purpose such rolls are cut so as to print a true diagonal corner; one corner being made for the beginning and the other for the end. Of course it is impossible to print long lines with only one revolution of the roll. The roll is run along the line from starting point until near the end, lifted off, and again placed on the spot just quitted, a little behind the starting point of the roll, so that this part does not show. This is repeated as often as the length of the line necessitates. In order to secure good corners, the roll is lifted just before reaching the corner and a corner tool is used for the corner itself. At no point should one be able to see where the roll was set on or taken off, and the result should be a straight, even line, showing no trace of inequality.
Fig. 81—Cover with laurel motive done in the Düsseldorf Technical School.
For single lines, the gold is generally taken up on the previously heated roll; but in using wider rolls it is better to lay the gold on with the tip and press it well down with surgical cotton wool.
Places where the gold did not stick or which look gritty must be sized afresh and once more tooled. The beginner generally finds that the gold does not stick at the point where he begins, a sure sign that he hesitated too long on commencing.
It has already been said that white of egg is used for making the gold adhere, and there are, indeed, very few materials requiring any other treatment, yet we know of a number of cases where white of egg alone is insufficient to fulfil this purpose—not, indeed, because it is unsuitable, but because the quality of the leather is such that the white of egg would be absorbed too quickly (calf, tanned sheep) or that it would take badly and unequally.