Paper and Its Uses/Chapter 5
CHAPTER V
FINISHING
Papers which have reached the stage described in Chapters III. and IV. still have much to be done to them before the consumer, stationer, or printer can receive them. Finishing varies with different papers. Hand-made paper requires sizing, drying, glazing, sorting, counting (sometimes cutting), and packing before it is ready for despatch. If the machine-made paper is for writing, it may be gelatine sized, followed by drying, re-reeling, glazing, cutting into sheets, sorting, counting, and packing into reams. Printing papers are finished with "machine" or with super-calender or water finish, and other papers with friction-glazed or flint-glazed surfaces, the other operations following as for other papers after glazing.
Tub sizing always means animal sizing. Some mills still prepare their gelatine from hide cuttings, parchment cuttings, and other materials which yield gelatine, but the tendency is to eliminate this process and to buy the gelatine in sheet form ready for use without any process other than reduction to a solution of such strength as is necessary. The tub or vat of size is prepared and kept at an even temperature, the paper is dipped or allowed to stand in the size, or there are machines which carry the paper slowly through the trough of gelatine. The size must permeate the paper in order to make the sizing effective. On emerging, the paper is squeezed to remove the excess of size, and the sheets are separated to prevent the paper from becoming a solid block.
The second visit to the drying loft prepares the paper for the last stages of manufacture. The drying is conducted at a moderately low temperature (for papermakers), not exceeding 80° Fahr., and when dry the paper has its bulk reduced and its surface improved by plate rolling, unless it is a drawing paper with a "not," that is, a rough surface. Plate rolling necessitates building a pile of paper, alternated with zinc plates a little larger than the paper, unbuilding and building of piles proceeding simultaneously as in the case of taking out set-off sheets and interleaving newly printed work. One girl takes the glazed paper, a second removes the plates, a third feeds the unglazed paper to the plates. When the pile is high enough it is lifted to the pressing rolls by a man who feeds it between the rollers, where great pressure is given, and the pile automatically returns to the front of the machine, and it is turned and placed for pressing the other way of the sheet. From two to a dozen pressings will be given according to the degree of finish required, and also to the hardness of the material.
Sorting, counting, and packing will complete the cycle of operations included in finishing, unless cutting to size is also necessary. Girls stand at long benches lighted with large windows, and have piles of paper before them for sorting into three classes—good, middling, bad—according to the degree or absence of defects. The middling paper showing slight defects is known as "retree," the reams are marked ╳ ╳ , and the paper is sold at 10 per cent, reduction on the price for good paper. Bad paper, showing glaring defects, is called "broke," the reams are marked ╳ ╳ ╳ , and it is either sold at a further reduction or is returned to be repulped. If the order is for specially watermarked paper, or is for all "insides" or good paper, the "retree" and "broke" will both return for re-making.
Machine-made writing papers which are to be sized with gelatine are usually first sized with resin, so do not come forward as waterleaf. The sizing room is long, high, comparatively narrow, containing a small sizing machine and numerous drying cylinders. The reel of paper is mounted on brackets in front of the sizing trough, the web passes between metal rollers, beneath the surface of the warm size, out and between squeezing rolls which remove the excess of gelatine, and then forward for drying. Up to the roof, and down to the floor, over skeleton drums, the web of paper travels until it is thoroughly dried, in a temperature equal to that of the drying lofts. At the end of the room the paper is reeled again, and when in a fit state goes either to the super-calenders, or, if the paper is to be plate-rolled, it is cut and the surface imparted as described for hand-made papers.
Papers which are merely to have "machine-finish," that is, the surface imparted by the calenders of the paper machine, receive no further treatment before being cut into sheets. Those papers which are to be super-calendered (S.C.) pass through a large super-calendering machine, consisting of a number of chilled iron rolls and rolls of compressed cotton or paper alternately. The weight of the rolls is enormous, and although extra pressure can be applied, it is not often necessary. A very high degree of finish can be given by means of the super-calenders, and the majority of papers with a glazed finish have passed through this machine.
Papers which are to receive a water finish are given a film of water on the surface just before the web passes between the rolls of the super-calender, and
Fig. 11.—Web Glazing Calender or Super-Calender.
(Built by Bertrams Limited, Sciennes, Edinburgh.)
as a result the mineral constituent of the paper is brought to the surface, and a very level finish, with a high degree of polish, is imparted to the paper.
Friction glazing produces a higher polish than the processes already described. The machine is simple in construction, consisting of a pile of three rolls, one of cotton between two of steel. The paper passes between two only, and the top roll, being driven at a higher speed than the others, burnishes the side of the paper against which it is driven in a much more effective manner than the super-calenders.
Flint-glazed papers are actually burnished by the surface of a stone passing rapidly backwards and forwards on the surface of the paper as it emerges from the rolls, giving a hard brilliant polish. The same degree of finish is imparted to some papers by the use of a number of brushes oscillating rapidly upon the paper as it travels over a large cylinder.
Cutting the reels into smaller widths and then into single sheets is the function of a number of ingenious machines. If a watermarked paper is to be cut to register, a single reel is mounted at the cutting machine, and the web is advanced the necessary distance and the division into sheets takes place by a knife. A boy watches the travel of the paper, and when the water-mark travels beyond or short of a pointer, a turn of a screw brings the next sheet into register. Single sheet cutters are used for other papers, the reel is mounted, run forward between slitting knives, and a swinging knife divides the paper into sheets. Another make of machine will take from one to seven reels, and the paper passing between the slitters is cut into sheets by a revolving cutter, which makes a clean cut the whole width of the web, and the sheets are dropped on a travelling felt, carried forward to the front of the machine, and knocked up by boys or girls. An automatic "layer" replaces the boys in some mills, keeping the piles knocked up. To prevent waste in cutting out blanks, envelope papers are cut at an angle, this being accomplished by swinging the frame carrying the revolving knife to the desired angle, and the papers are delivered in sheets ready for the envelope maker.
From the cutting machines the paper is taken to the "salle"—the sorting and packing room of the paper mill. A number of girls rapidly examine every sheet of paper, withdrawing those sheets which fall below the papermaker's standard of perfection, sorting into retree and broke proceeding as in the case of hand-made papers. Counting, cutting, and packing take place very quickly after the paper is sorted. The nimble fingers of the counters turn up the edge of a quantity of paper, the fingers of the other hand run down the edges quickly, counting into reams with extraordinary accuracy. Some papers are trimmed before packing, while others are cut from double to single sheets. Wrappers are carefully folded round the paper, and fastening is done by means of string, tape, or paper tape according to the size and weight of the reams.
As will be seen from "Paper Trade Customs," on page 135, the number of sheets to the ream is a varying quantity. A ream may consist of 472, 480, 500, 504 or 516 sheets.
In hand-made papers a mill ream consists of two qualities of the same paper, whether the paper is bought as good or retree. If the paper is good it will consist of 18 quires of insides or best paper, each quire containing 24 sheets, and two quires of outsides or slightly inferior paper, the quires containing 20 sheets each. "Retree" paper is marked on the outside by two crosses , and the mill ream will be 472 sheets, whether the paper be good or retree. The price of a ream of insides is usually 10 per cent. above the price for a mill ream.
Machine-made paper is good, retree, and outsides, the prices being 10 and 20 per cent. less for the second and third qualities respectively. Paper is usually supplied in inside reams of 480 sheets, that is, all good paper, but the papermaker may supply mill reams of 480 sheets, but with a quire of outsides at the top and bottom. The ream of 480 sheets is also known as the stationer's ream—writing, drawing, cartridge, and fancy papers being packed in that quantity. Paper classed as news is packed in 500's, envelope papers in 504's, and many printing papers in perfect or printer's reams of 516 sheets.
The variety of reams suggests that it might be well to move for a standard ream of 500 sheets. The present system makes for confusion in giving out paper, keeping stock, estimating and pricing out, and a simplification should be welcomed.