From Paper-mill to Pressroom

by William Bond Wheelwright

Fuzz, or hairiness, usually occurs on the wire side of the sheet. This is due partially to the stock, soda pulp being especially likely to fuzz. It is also due to overdrying, and sometimes to the action of the suction boxes, which if worked too hard cause the surface fibers to stand on end.

“Hairiness,” or fuzz is more apt to occur on antique and other light finishes, but calendering will not entirely overcome it, and such papers as would be fuzzy uncalendered, become fuzzy with handling.

In fact, the durability of the surface may well be tested by rubbing the paper between the fingers. In this way, too, one judges the “feel,” which of all qualities of paper is perhaps the most difficult to express, but usually described as hard, soft, mellow, harsh, rough, smooth.

In highly calendered papers, well closed and evenly finished, the light will be reflected uniformly, as from a well-polished table-top; but if the formation is “wild,” there will be a blotchy look as the small knots of unevenly distributed fibers cause thick and thin areas, and the thick ones get harder squeezing through the calender rolls and, consequently, a higher finish.

Another cause for unevenness in finish is a variation in the thickness of the paper as it is made on the machine. This unevenness runs lengthwise in streaks, and may originate on the wet end of the machine if the pulp is not deposited uniformly.

Again, the pressing may be faulty at the press rolls, causing a thin streak. Naturally, the thin part of the paper dries more readily than the thick, and as even surfacing depends partly upon even dissemination of moisture in the sheet, a poorly pressed sheet would have a faulty finish. Dirty felts also cause uneven drying, as water can not be evenly squeezed through a felt the pores of which are partially choked. Lastly the unevenness may be caused by the calender rolls themselves being in poor condition.

It is easy to detect thin areas by examining paper in a pile, as a pile of papers of uniform thickness will be practically level on top.

Papers for half-tone printing, whether coated or uncoated, should be even in formation, thickness and surface, otherwise the printer’s “make-ready,” which is designed to offset inequalities in the plates, will be discounted by inequalities in the paper.

There are some special papers in which unevenness in formation and finish are intentional, on account of the unusual effects thus gained; and other papers, such as wrappings, where such niceties of the paper-makers’ art are of little importance.

Opacity.—Opacity may easily be judged, although it is difficult to express it in any accurate terms, by placing the papers to be compared side by side over a printed page, the relative merits in this respect may be immediately perceived.