From Paper-mill to Pressroom

by William Bond Wheelwright

The appraisal of a specimen of paper differs from testing in that an appraisal comprehends the value of an object in relation to its usefulness and marketability, whereas testing is merely an arbitrary method of expressing the chemical or physical properties of the object. The knack of appraising can be acquired only through practical experience; and the ability to make tests is gained only by careful technical training.

In the majority of cases a satisfactory appraisal may be given without chemical or physical tests, but these are cases when the superficial characteristics, such as color, finish, feel, etc., are the prime qualifications, and such considerations as fiber contents, freedom from impurities, exact tensile strength etc., are of negligible importance.

Although experience, only, leads to the knack of appraising paper, certain points might be suggested with benefit to the beginner which would assist him to an earlier acquirement of the art.

Color.—Color being a purely relative term as applied to the variations in so-called “white” papers, it is necessary to make comparisons with accepted standards of the various grades in order to arrive at conclusions.

In common parlance, white papers may be described as natural, light natural, white, blue-white, pink-white. Natural papers are those in which a minimum of artificial coloring has been added, and the brilliancy of shade depends entirely upon the quality of the stock.

Almost all paper is colored to some degree while the stock is in the beater, and the minimum quantity of order of paper, which any mill will make on a special run is usually limited by the contents of one beater, and, on account of the time required to wash up, the cost of special colors is increased. Rose-pink and blue are the colors used in modifying the natural color of any beater of pulp to produce a white paper. The so-called “white color” of the cheaper grades of papers is ordinarily gained by a comparatively heavy use of blue, and by comparison with a white paper of good quality the blueness is decidedly noticeable. In judging color, it is well not only to look at the surface, but also to examine the paper when held up against the light, making comparison with some acceptable standard, also noting the clearness of the stock, as indicated by the sharpness of definition of the shadows of the fingers which hold the sheet. This comparison is affected, of course, by the bulk of the paper, but two papers of about equal bulk may be fairly compared in this way. Any judgment as to shade is, in part, only a question of taste. Permanency of color may easily be determined by exposing a portion of a sheet to sunlight for a few hours and noting any alteration in color.

Formation.—While examining a paper for color and clearness, the formation of the sheet should also be observed. In general, a close, even formation is to be desired. Fibers of the same approximate length may be loosely or evenly formed, according to the skill of the machine-tender. The longer the fiber, the harder it is to get a close, even formation, and it should be remembered that these two qualifications are to a greater or less extent contradictory.

Finish.—Whatever the finish of paper, the two sides of an ideal sheet would look exactly the same. In most papers made on a Fourdrinier machine the impress of the wire is discernible, and there is a perceptible difference in texture between the “wire,” or bottom, side and the “felt,” or top, side, the one tending to reproduce the texture of the wire cloth, and the other the weave of the felts.

Some manufacturers have perfected their processes to a degree that renders these differences imperceptible. Papers made on cylinder machines of more than one vat are apt to be more even-sided, as the contact with the wire of the molds is less protracted and there is considerable pressing of the web between two felts as it is carried along.

The evenness of the finish, and the fineness of texture over all parts of a sheet, may best be judged by holding it aslant to the light. This also discloses whether the paper is “fuzzy” or free from lint.