Conditions of Beating.—About A.D. 1700 there began a great epoch in the history of paper-making. With the invention of the Hollander engine about A.D. 1670, the process of disintegration was greatly hastened, because it was possible to reduce the half-stuff much more readily. The substitution of the idea of plain “beating” by a principle which combined the gradual isolation of the individual fibres with a splitting up of those fibres lengthwise and crosswise was not only an advantage in point of economy of time and cost, but also a material advance in the possibilities of greater variations in the finished paper.
The conditions of the process of beating carried out with a Hollander permit of considerable alteration, so that these changes in the fibre are not surprising when properly understood. In fact, it is now conceded that a close study of the theory and practice of beating is likely to bring about still more remarkable improvements in this important department of the paper-maker's work. The quality and character of the paper made may be varied with—
(1) The origin of the raw material, e.g., rags, esparto, or wood;
(2) The condition of the material, e.g., old or new rags, green or mature esparto, mechanical or chemical wood pulp;
(3) The time occupied in beating, e.g., four hours for an ordinary rag printing and twelve hours for a rag parchment;
(4) The state of the beater knives, e.g., sharp tackle for blottings and dull tackle for cartridge papers;
(5) The speed of the beater roll, also its weight;
(6) The rate at which the beater roll is lowered on to the bedplate;
(7) The temperature of the contents of the engine.