Paper & paper making, ancient and modern

by Richard Herring

In some instances, when the paper being made is sized in the pulp with such an ingredient as resin, the felt becomes so completely clogged in the space of a few hours, that unless a very great and apparently unnecessary length of felt be employed, a considerable waste of time is constantly incurred in washing or changing the felt. To obviate all this—whether waste of time or waste of felt—I have suggested in one or two quarters, the propriety of passing the felt, as it returns from conducting the paper to the heated cylinders, through a trough of water, and while travelling through the water to apply suction boxes to both the upper and lower surface of the felt, which by an alternate action, might be made sufficiently powerful to remove all impurity, without in any way obstructing the progress of the felt; which if found necessary, might be assisted, while at the same time the felt would be restored to its original condition, by employing a suction roller to which a steady motion was given in connexion with the machine.

The operation of the manufacture will now be apparent. The pulp flowing from the reservoir into the lifter, and thence through the strainer, passes over a small lip to the continuous wire, being there partially compacted by the shaking motion, more thoroughly so on its passage over the air boxes, receiving any desired marks by means of the dandy roller passing over the continuous felt between the first pressing rollers, then turned over to receive a corresponding pressure on the other side, and from thence off to the drying cylinders, which are heated more or less by injected steam; the cylinder which receives the paper first, being heated less than the second, the second than the third, and so on; the paper after passing over those cylinders, being finally wound upon a reel, as shown, unless it be printing paper, which can be sized sufficiently in the pulp, by an admixture of alum, soda, and resin, or the like; in which case it may be at once conducted to the cutting machine, to be divided into any length and width required. But, supposing it to be intended for writing purposes, it has first to undergo a more effectual method of sizing, as shown in the accompanying drawing. The size in this instance being made from parings obtained from tanners, curriers, and parchment-makers, as employed in the case of hand-made papers. Of course, sizing in the pulp or in the engine offers many advantages, but as gelatine, or animal size, which is really essential for all good writing qualities, cannot at present be employed during the process of manufacturing by the machine without injury to the felts, it becomes necessary to pass the web of paper, after it has been dried by the cylinders, through this apparatus.

SIZING APPARATUS

In most cases, however, the paper is at once guided as it issues from the machine, through the tub of size, and is thence carried over the skeleton drums shown, inside each of which are a number of fans rapidly revolving; sometimes there are forty or fifty of these drums in succession, the whole confined in a chamber heated by steam. I have seen a paper machine with the sizing apparatus attached, which from the wire-cloth where the pulp first flows on, to the cutting machine at the extremity, measured no less than one thousand feet. The advantage of drying the paper in this manner over so many of these drums is, that it turns out much harder and stronger, than if dried more rapidly over heated cylinders. Some manufacturers adopt a peculiar process of sizing, which in fact answers very much better, and is alike applicable to papers made by hand or by machine, provided the latter description be first cut into pieces or sheets of the required dimensions. The contrivance consists of two revolving felts, between which the sheets are carried under several rollers through a long trough of size, being afterwards hung up to dry upon lines, previously to rolling or glazing. The paper thus sized becomes much harder and stronger, by reason of the freedom with which the sheets can contract in drying; and this is mainly the reason why paper made by hand continues to be so much tougher than that made by the machine, in consequence of the natural tendency of the pulp to contract in drying, and consequently becoming, where no resistance is offered, more entwined or entangled, which of course adds very considerably to the strength and durability of the paper. In making by the machine, this tendency, you will observe, is completely checked.

The next operation which we have to notice, now that the paper is finished, is that of cutting it into standard sizes. Originally, the reel upon which it was finally wound, was formed so that its diameter might be lessened or increased at pleasure, according to the sizes which were required. Thus, for instance, supposing we wanted to cut the web of paper into sheets of 18 inches in length, we should either lessen the diameter of the reel to 6 inches, and thus the circumference to 18 inches, or if convenient increase it to 36 inches, afterwards cutting the paper in two with a large knife, similar in size and shape to that employed by a cheesemonger; the width of the web being regulated by the deckle straps (Q) to either twice or three times the width of the sheet, as the case might be. However, in regard to the length considerable waste, of necessity, arose, from the great increase in the circumference of the reel as the paper was wound upon it, and to remedy this, several contrivances have been invented. To dwell upon their various peculiarities or separate stages of improvement, would, no doubt, prove to the general reader of little comparative interest, I shall, therefore, confine my attention to a brief explanation of the cutting machine, of which I have given an illustration, and which is unquestionably the best, as well as the most ingenious, invention of the kind.

The first movement or operation peculiar to this machine is that of cutting the web of paper longitudinally, into such widths as may be required. And this is effected by means of circular blades, placed at stated distances, which receive the paper as it issues direct from the other machinery, and by a very swift motion, much greater than that at which the paper travels, slit it up with unerring precision wherever they may be fixed.

A pair of those circular blades is shown in the drawing (a), the upper one being much larger than the lower, which is essential to the smoothness of the cut. And not only is the upper blade larger in circumference, but it is also made to revolve with much greater rapidity, by means of employing a small pinion, worked by one at least twice its diameter, which is fixed upon the same shaft as the lower blade, to which the motive power is applied. The action aimed at is precisely such as we obtain from a pair of scissors.

The web, as it is termed by the paper-maker, being thus severed longitudinally, the next operation is that of cutting it off into sheets of some particular length horizontally; and to do this requires a most ingenious movement. To give a very general idea of the contrivance, the dotted line is intended to represent the paper travelling on with a rapidity in some cases of 80 feet per minute, and yet its course has to be temporarily arrested while the required separation is effected, and that too without the paper’s accumulating in any mass, or getting creased in the slightest degree.