Double-Sized Paper.—This term is applied to paper which, after being sized in the engine in the usual way, is afterwards "surface sized," as it is called, with animal size in the manner described.
Respecting the drying of paper after it has been tub-sized there seems to be some difference of opinion as to whether it is best to hang it in a loft to dry or to dry it over the cylinders of a drying machine. Upon this point the New York Paper Trade Journal makes the following remarks:—"When the paper is passed through the size-tub, it is again wet; the fibres expand, and their hold on each other is relaxed. Now it must make a difference to the subsequent strength and quality of this paper whether it be hung up in a loft to dry or run over a drying machine. If it is hung in the loft no strain is put upon it and the fibres are at liberty to shrink, or slowly contract, in all directions; whereas if it is run over a drying machine, consisting of from 50 to 100 reels, the longitudinal strain prevents the fibres from shrinking and reassuming their normal position in that direction. Attempts have been made to obviate this defect by regulating the speed of each section of the machine in such a manner as to allow for the shrinking, but this only remedies the evil by preventing the paper from breaking as it travels over the machine. Everything else being equal, it would seem that loft-dried paper must be superior to that dried over the drying machine. Our home manufacturers endorse this view, inasmuch as they continue to prefer the system of loft-drying to the less expensive machine methods."
Mr. Wyatt's Remarks on Sizing.—Mr. James W. Wyatt, in a paper on the "Art of Paper-making,"[26] makes the following observations on engine-sizing and animal-sizing which will be read with interest:—"Engine-sizing renders the paper fully as non-absorbent as animal size. The latter penetrates the sheets only slightly and forms a coating or skin on each surface, whereas the engine size surrounds each fibre and impregnates the whole mass. Surface-sizing, however, produces a stronger, firmer sheet, and is smoother for the pen to travel over; the manufacturer also gets the benefit in the price of the paper of the additional weight of the size, amounting to 7 per cent. on the average. On the other hand, as the animal size is mostly a skin on the surface, if the coating be broken anywhere by the use of a knife in scratching, the paper will only imperfectly resist ink in that place, a great disadvantage for account and office-books and ledgers. Engine-sized paper is much cheaper to produce than animal sized, and is therefore used principally for the lower qualities of writings and for almost all kinds of printings where firmness and smoothness is not so much a desideratum. Most tub-sized papers have a certain portion of engine size mixed with the pulp. This not only ensures the thorough sizing of the sheet, but also is a measure of economy in reducing the absorbing power of the paper for the animal size. Papers for ledgers and office-work are best given an extra proportion of engine size to ensure their ink-resisting properties, and they are also sized by hand in animal size and loft dried." The following rough estimate of the comparative cost in materials and wages of engine-sizing and animal-sizing paper may be of interest:
| Engine-sizing, per 20,000 lbs.:— | |||||
| £ | s. | d. | |||
| Materials | 5 | 2 | 0 | ||
| Wages | 0 | 12 | 6 | ||
| ————— | d. | ||||
| Total | £5 | 14 | 6 | Cost per lb. = | 0·068 |
| ========== | |||||
| Animal-sizing, per 20,000 lbs.:— | |||||
| £ | s. | d. | |||
| Materials | 36 | 0 | 0 | ||
| Wages | 4 | 10 | 0 | ||
| —————- | |||||
| Total | £40 | 10 | 0 | ||
| =========== | |||||
[CHAPTER XII.]
MAKING PAPER BY HAND.
The Vat and Mould.—Making the Paper.—Sizing and Finishing.
Under the old system of making paper by hand, the rags were reduced to a fine state of division by a process of retting, or slow putrefaction. The rags were first washed in water, and then piled in heaps, in which condition they were allowed to remain until they became tender, that is, readily pulled asunder by the fingers. During the decomposition the rags not unfrequently became rotten in some portions of the heaps, thus involving considerable loss of fibre. The rags were next placed in a strong chest, in which iron-shod stamping rods were fitted, and these by their continued action gradually reduced them to a pulp. The stampers were eventually superseded by the beating-engine, the invention of a Dutchman, which received and still retains the name of the "Hollander." Other machines, as the duster, washing and breaking engines, and the beating engine, have entirely taken the place of the older system, which required the work of forty pairs of stamps for twenty-four hours to produce one hundredweight of paper.