Page:Paper and Its Uses.djvu/44

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PAPER AND ITS USES

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