Paper and Its Uses/Chapter 14

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Selection of paper to suit a particular job calls for experience in handling both the finished work and the plain paper. Judging papers as being equal to patterns or samples, and forming an opinion of comparative values, are also to be gained only by long experience. A few guiding principles, without making a royal road, may render the journey somewhat less laborious.

The varieties of papers already described—writings, printings, coated, and other papers—are accompanied by indications of their general purposes, and the inexperienced should be kept from making bad blunders. Common sense will prevent the mistake which is still perpetrated of printing a half-tone block on a laid paper, or a paper with a heavy watermark. The laid lines and the watermark show up through the half-tone impression and spoil the picture. Half-tone work demands a perfectly smooth paper, coated or a good super-calendered paper being the best.

Very few papers are identical in finish on both sides of the sheet, and it should be the first thing taught to the apprentice that all one-sided work should be printed on the right side of the paper. A matter which is seldom referred to is the position of the watermark. When cutting paper, the paper should not be turned so that in a ream one-half of the paper has the watermark reading correctly, while on the other half it is upside down. If the paper is ruled or printed in the sheet, the pens and type or transfers should be arranged to keep the watermark the right way. In the case of folded and stitched work this is not possible without special watermarking, but for all stationery these precautions should be taken.

When judging paper or cards it must always be remembered that a sheet may compare very badly with a small piece, therefore when making comparisons the sizes of the samples of paper or card should be cut to the same size. Only by adopting this practice can weight, colour, and texture be judged accurately.

Choosing a paper suitable for the work in hand is simplified when one knows what is used for similar work. For ledgers, account books, and all work of that character, a strong, tough, well-finished paper, capable of taking writing ink easily, and able to bear ink after erasure should be used. An opaque all-rag, azure laid, tub-sized paper, of moderate weight, 34 Ib. in writing medium, is the most suitable paper. For loose-leaf ledgers a thinner, tougher paper is desirable, as the leaves must lie closely and withstand the strain of frequent handling. For cheap account book work engine-sized papers are obtainable, very fair in appearance, but not possessing all the qualities of the better paper specified, or the extra cost of the latter could not be justified.

The ideal paper for printed books is an all-rag paper, moderately sized, with antique or rough finish, excellent in handling and appearance, but the price precludes its use for any but the most luxurious editions. For ordinary bookwork, white paper with dull or machine finish, quite opaque, substance equal to 30 lb. demy, provides a serviceable paper where no illustrations, or line blocks only, appear. If half-tone illustrations are included, a super-calendered paper, slightly toned, is very suitable. When half-tones of very fine grain are used, it may be necessary to print on art paper throughout, or the illustrations printed on art paper and the body of the work on a printing paper of exactly the same shade as the coated paper. Mixture of shades in books should be avoided as far as possible. The practice of printing sections of magazines on different papers is growing, but is to be deprecated.

For works which have to make bulky volumes for a comparatively few pages, featherweight papers are employed. These in 80 lb. quad crown will usually be chosen, wove or laid as fancy dictates. Some of the wholesale stationers state on the samples the thickness or bulk of a volume of a definite number of pages, this information serving as a guide in selecting paper to produce the thickness required in a volume. When a series of books is issued it is sometimes desired to have all the volumes of equal bulk. This is attained by adopting papers of different thicknesses; thus a book of 500 pages is printed on a paper about half the thickness of that used for a volume of 256 pages. The range of substances in which papers are supplied renders this arrangement comparatively easy.

The large variety of fancy papers for jobbing work calls for little comment. Avoid hard papers for programmes unless there is plenty of time for the ink to dry, or gloves will bear the printer's imprint. For outdoor functions coloured papers, if employed for programmes or similar jobs, must not be affected by moisture. Colour may decorate summer costumes if the programmes printed on coloured paper are sat upon. Art paper, too, is unsuitable for outdoor exposure in our changeable climate, and its use is to be couraged for sport programme work. Coloured poster papers must be unaffected by rain. Many coloured papers render printed matter exceedingly difficult to read by artificial light.

The incongruity of a common cover paper to a booklet printed on a good printing paper, or vice versa, is to be avoided. Select papers for the inside and cover bearing both in mind, and if expense is to be considered, a compromise in quality may be effected. It is not always easy to persuade the consumer to select the very best paper for office stationery, but the choice should be made with a view to create a good impression. Remember always, too, that printing demands good paper to produce the most satisfactory effect.

For lithography the work in hand frequently dictates the quality of paper to be used. Offset printing, certainly, has enabled the lithographer to print on papers unsuitable for direct stone printing, but in all work the right paper produces the best result. Fluffy papers, such as featherweights, however, are impossible for lithography. Loose of texture, with a tendency to shed fibre, the paper clogs the printing surface, and in such circumstances the best work is unattainable. Charts and maps are printed on strong, durable papers, and the manufacturers' chart papers will be found to conform to the description given.

Colour work requires a paper which will give full effect to the colours superimposed upon its surface, white paper being most suitable for the purpose, the kind of paper employed being governed by the destination of the printed work. Chromo paper, litho. paper, M.G. poster paper, will be used according to the method of exhibition of the work, as calendars, labels, book illustrations, or posters. Work which is to be varnished may be printed on litho. paper, which is sized and varnished after printing, or a varnishable paper, one that is hard-sized and finished in the manufacture, may be used, varnish being applied without previous sizing, as soon as the ink is dry. A thick litho. paper is seldom as strong as a thinner one, and with the greater thickness goes more liability for the surface to pluck.

The thinnest and commonest papers should not be chosen for set-off or interleaving sheets. Although many papers, when printed, absorb the ink and hasten the drying, it must be remembered that printer's ink, like paint, dries by oxidation, and the more freely air can reach the film of ink the quicker and more thorough will be the drying. A rough surfaced paper is most suitable for interleaving, as it will not stick to the printed matter, and it allows air to penetrate between the sheets. For interleaving colour work in which bronze is used at all, a paper of fair quality must be used, for common papers may contain chemical residues which will affect the brightness of the bronzed work. Paper equal to 24 Ib. demy will serve admirably, and may be used repeatedly.

Proofs should be printed upon the paper which is to be used for the job, if that is possible. Galley proofs require a paper which is moderately sized, not too soft, or corrections made in ink may be undecipherable from the spreading of the ink.

It is not difficult to distinguish between the right and wrong sides of paper, and little excuse can be made for the printer who uses the wrong side. Flat papers are usually packed with the right side uppermost; if the paper is folded, the right side is utwards. There is a slight diversity of practice among paper-makers, but the general rule is as stated. In a very few cases of watermarked papers the watermark can be read from both sides of the sheet, but the general rule is that the right -side of the sheet is that from which the watermark can be read. In machine-made papers it is the upper side of the paper as it is made, but in hand-mades the right side is the under side which receives the watermark. The watermark is in reverse upon the mould or the dandy roll, and is fixed on the impressionable pulp by slight compression or displacement of the fibres. In papers without water-marks it may be taken that the smoother side is the right side. The wrong side of machine-made papers bears the impress of the woven wire upon which they were made. The wire mark is fixed by various means, such as the pressure of the dandy roll, the action of the suction boxes, and the pressure of the couch rolls. Blotting paper, although not subjected to all these forces, shows the wire mark so plainly as to serve as a guide to what one may expect to find in other papers which are more highly finished. Looking along the surface of the paper will sometimes reveal this mark, when it is not possible to detect it by looking through the sheet. The wire for hand moulds is much coarser than the wire cloth of the machine, and as the pressure of the pulp is not great, and the fibre is moderately long, couching nearly obliterates the woven wire mark and makes it less easy to distinguish between the right and wrong sides of hand-made wove papers. In a laid mould the wires displace fibres, and the paper is immeasurably thinner at the places where the wires of the mould occur, but these are the only wire marks on the paper. A dandy roll makes the laid wire marks on the right side of machine-made paper in addition to the woven wire marks on the wrong side, so the distinction between right and wrong sides is easily made in machine-made papers. The smooth side of M.G. papers is the right side. M.G. poster papers are rougher on the wrong side to make the posting of the bills an easier matter.

The wire marks assist one in distinguishing between hand-made and machine-made papers. It is clear that all machine-made papers have a wire mark on the wrong side, even if laid or watermarked. The water-mark of the hand mould is fastened over the wire, so the watermark will never show wire marks. Looking through the paper, observe whether the watermark has any small woven wire marks ; if it has, it is undoubtedly machine-made. A laid paper which shows woven wire marks is of course the product of the machine.

Coloured papers may vary in shade on the two sides. This variation is more frequently seen in papers which are coloured by pigments than in those dyed with aniline colours. Blue papers, with ultramarine in their composition, tend to be slightly lighter on the wrong side of the sheet. The causes of this are different in hand-made and machine-made papers. In hand-mades the colour has a tendency to gravitate to the bottom of the mould, which is the right side of the paper, while in machine-made papers the action of the suction boxes is apt to draw some of the colour away from the under side, leaving the right side slightly darker. Thus difference in shade of the two sides is not a guide to distinguish between hand- and machine-made papers.

To recall the methods of manufacture. The mould of hand-made papers receives a shake each way, felting the fibres evenly. The machine wire receives a side-shake which is only effective for a short period as long as the pulp is in a state of suspension and as soon as the water has drained away the shake ceases to take effect, consequently the majority of the fibres are parallel to the direction of the flow of the pulp. Some fibres are crossed or felted ; but taking the web of paper, it is more easily pulled apart across its width than in the direction of its length. The fibres are fixed and are dried in a state of tension, so that the fibres in the direction of the flow (known as the machine direction or the grain of the paper) are fully extended, and subsequently expand but little in length, but may do so in width or diameter.

The direction of the fibres serves to distinguish between hand- and machine-made papers. Tearing a piece of hand-made paper will result in ragged tears, very similar both ways of the sheet. A piece of machine-made paper shows a ragged tear in one direction, and a much straighter tear in the other. The straighter tear is in the machine direction. If a circle about three inches in diameter is cut from a hand-made sheet and thoroughly damped on one side, the paper will curl slowly and unbend again. If a similar piece is cut from machine-made paper and treated in the same way it will curl more quickly into a cylinder and remain rolled up for some time. This not only serves as a distinction between the two papers, but, in machine-mades, shows the machine direction which is parallel to the axis of the cylinder of paper. By marking the sheet before the circle is cut, the machine direction of the sheet can be determined.

Strips cut from the sheets, one from each way, 7 inches long by I inch wide, held between the finger and thumb and allowed to incline at an angle of 60, will behave differently according to the method of manufacture. Hand-made strips will keep together, because the fibres are equally distributed, while strips of machine-made paper will separate, owing to the difference in the direction of fibres. The strips should be inclined first to the right and then to the left to ensure correct conclusions.

Hand-made paper has four deckle edges, but imitation hand-mades also have these, and mould-made papers are similarly marked. Imitation hand-mades, being machine-made, are distinguishable by the means enumerated above, and comparison with the edges of known hand-made paper will be the quickest method of distinguishing between real and imitation deckle edges.

Mould-made papers are not easily distinguishable from hand-made papers. The deckle edges are not always alike on all four sides as they are in hand-made papers. Testing on the Leunig machine (see page 99), they will usually reveal a difference which it is not possible to discover from looking at the sheet. The German paper experts declare it impossible to differentiate with certainty between the two kinds of paper, while a papermaker who manufactures both varieties usually has but little difficulty in naming them correctly.

Comparison between Hand-made, Mould-made, and Machine-made Papers

Tests made on Leunig's Machine (see page 99),
Papers of same size and substance

Description of
Stronger Direction. Weaker Direction. Mean of Two Directions.
Elongation. Tensile
Elongation. Tensile
Lb. Per cent. Lb. Per cent. Lb. Per cent.
Hand-made 25.5 3.9 22.1 5.6 23.8 475
Mould-made 26.8 4.8 20.8 4.7 23.8 475
Machine-made 26.5 3.7 16.0 5.7 21.3 470

The figures given are the mean results of five tests.

Tearing paper as a method of comparing strength is one of the simplest as well as one of the surest methods. Paper has to withstand tearing stresses, and the paper which ruptures with most difficulty is usually the most resistant to wear. Tearing will reveal whether the paper is composed of long or short fibres, and whether it is tough or brittle, and is a method of testing which requires no apparatus.