New Method of Bleaching.—Young's Paraffin Oil Company have recently introduced what they term an "intermediate oil for paper-making," to be used with alkali in the boiling of rags and esparto, for the purpose of increasing the bleaching power of the powder, and producing a softer pulp, at the same time having no smell. Several well-known paper-makers have tried, and speak favourably of it. The quantity of oil to be added to the caustic varies for different stock, but may be said to average about 1½ gallon per ton.[20]
[CHAPTER X.]
BEATING OR REFINING.
Beating.—Mr. Dunbar's Observations on Beating.—Mr. Arnot on Beating Engines.—Mr. Wyatt on American Refining-Engines.—The Beating Engine.—Forbes' Beating-Engine.—Umpherston's Beating Engine.—Operation of Beating.—Test for Chlorine.—Blending.
Beating.—One of the most important operations in the manufacture of first-class paper is that of beating, by which the half-stuff becomes reduced to a fine state of division, and the fibres which, in the condition of half-stuff, are more or less loosely held together in a clotted state, become separated, and are thus put into a condition in which they will intertwine with each other, or felt, as it is termed, when submitted to the vibratory motion of the wire-cloth of the paper machine. The beating-engine, or beater, as it is commonly called, much resembles in construction the washing- and breaking-engine, but since it is required to still further reduce the pulp to a condition suitable for paper-making, the knives of this engine are more numerous and are made to revolve more rapidly. In this engine the half-stuff is cleansed from bleach, hydrochloric or sulphuric acid—whichever acid may have been used in the bleaching—chloride of calcium, and the various products resulting from the decomposition of the chloride of lime. In this engine, also, the loading, sizing, and colouring materials are worked up with the pulp, and the stuff fully prepared for its final transfer direct to the paper-machine. Before describing the various forms of beating-engines which have been from time to time introduced, including some of the most recent types, to which special attention will be drawn, we purpose quoting some observations of well-known experts in paper manufacture which will be read with interest, since they fully explain the importance that attaches to the proper manipulation of the beating-engine for the production of paper of high quality.
Mr. Dunbar's Observations on Beating.—There is no operation of the paper-mill that requires more careful attention and experienced judgment than that of beating, or refining, to bring the pulp to the finest possible condition for paper-making; in this department, Mr. Dunbar urges, "none but thoroughly efficient men should be employed, for it is here that the paper is really made—that is, the quality of the paper produced at the paper-machine will be in proportion to the treatment the material has received; and if the half-stuff sent to the beating-engines is not subjected to judicious manipulation and careful preparation for the special paper to be made, all future doctoring will prove unsatisfactory."
Mr. Arnot on Beating Engines.—On this subject Mr. Arnot says:—"Upon the management of the beating-engine the character of the paper produced largely depends. What is wanted is not a mincing or grinding of the fibre, but a drawing out or separation of the fibres one from another; in fact, the name of the machine indicates pretty accurately the nature of the action required—beating. Long, fine fibres can only be produced [obtained] by keeping the roll slightly up off the bed-plate, and giving it time to do the work. Sharp action between the roll and the bed-plate will, no doubt, make speedy work of the fibre, but the result will be short particles of fibre only, which will not interlace to make a strong felt. Indeed, the action I refer to will reduce the long, strong fibre of linen to little better than that of wood or straw. Practice and careful observation can alone make a good beater-man, and for the finer classes of paper none but careful, experienced men should be entrusted with the management of the beating-engine. Sometimes the operation is conducted in two successive engines, the first being called the intermediate beater, but I have hitherto failed to see wherein the advantage of this system lies. The time usually occupied in beating esparto for printing-paper is about four hours, while for rags the time may vary from four to twelve hours, or even more." This, however, depends upon the nature of the rags themselves, and the purposes to which they are to be applied.
Mr. Wyatt on American Refining-Engines.—Referring to the engines adopted in America, Mr. Wyatt says:—"There are various modifications of the original Jordan, the principal ones being the Marshall, Jeffers, and improved Jordan; but I gathered that experience proves the Jordan type to be the most practical and efficient in the end, and is one of the most generally used. One Jordan is required for each machine, refining all the stuff supplied to it. The roll, or plug, runs from 350 to 400 revolutions per minute, the horse-power consumed varying from 25 to 40 horse-power according to the work done, and an engine will do up to 1,000 lbs. of pulp per hour. The time saved in the beating-engine by the use of the Jordan is just about one-third of what would otherwise be necessary, that is to say, pulp requiring otherwise six hours beating only takes four hours if finished in the Jordan. The half-beaten pulp is emptied into a stuff-chest, and the Jordan is furnished with a small stuff-pump and service-box, just as at the paper-machine what the Jordan does not take flows back again into the chest: the pulp from the Jordan is run into the ordinary machine stuff-chests. The finished pulp can be taken from the Jordan at three different levels from the circumference of the roll, or plug. If the pulp is wanted 'free,' it is drawn from the bottom of the engine; if wanted 'wet,' or well greased, it is drawn from the top; and if medium from the centre."