# Paper and Its Uses/Chapter 8

CHAPTER VIII
PRINTING PAPERS
There is considerable variety in printing papers, as regards fibre, sizing, and surface. As generally understood, printings are papers of good colour, not too hard-sized, of good surface, even in texture, fairly opaque, showing a clear look-through, free from specks and spots. The fibrous composition will depend largely upon the price. An all-rag paper is a splendid white paper, soft to print upon, pleasant to handle, very durable, and a type of moderate colour printed with a good black ink gives a very rich appearance on such paper. Hand-made, Dutch hand-made, mould-made, and machine-made rag papers are the papers for very special editions. Special moulds or dandy rolls are sometimes made for these papers to secure a distinctive appearance.
High-grade printing papers are produced from a mixture of rag and esparto fibres, a soft paper, taking a good finish, being produced. A blend of chemical wood and esparto, skilfully manufactured, produces a very good printing paper for all ordinary purposes, and papers composed entirely of chemical wood may be good or indifferent according to the treatment and skill devoted to their production. Sulphite papers tend to be harsh and transparent, but a mixture of soda pulp partly counteracts these faults, and even if it is not quite as soft as an esparto mixture, excellent results in ​printing can be obtained if the fibres have been carefully beaten and blended. Papers containing mechanical wood are classed as common printings, and are suitable only for common work. A small proportion of mechanical wood may not be noticeable in the finished paper, but when a large proportion is used, greyness of colour and poorness of appearance are sure indications of the low quality of the material. Hand- and mould-made papers have no mineral filling in their composition. For machine-made papers the addition of a small proportion enables them to take a very good finish. The amount of china clay present in the finished paper should not exceed 10 per cent, of the total weight.
Hand-made and mould-made printings are tub-sized and plate-rolled, without giving a high glaze to the paper. Machine-made printings are engine-sized, hard or soft according to the use to which the paper is to be put, and sometimes the surface will govern the sizing, some papers being hard-sized and super-calendered, others soft-sized and with only machine finish. As a matter of fact, super-calendered printings are used largely for illustrated work, and with half-tone blocks the ink must dry thoroughly and fairly quickly, so the paper is not hard-sized. All thin printings require to be well sized to prevent the ink sinking right through the paper, and most papers with machine finish, excepting the commoner news, are usually well sized, and coloured printings, too, incline to hard-sizing.
The best Bible papers are made of rag fibres with a fair amount of loading, and some starch to ensure opacity and good printing qualities. The Oxford India paper is still manufactured under special conditions which are kept secret, but there are many imitations which serve excellently for the purpose of thin paper editions. The graphic demonstration of the difference ​between the thickness of the "Encyclopaedia Britannica" printed upon India paper and ordinary printing paper will be fresh in the minds of most readers.
Toned papers are made of the same materials as white paper, the creamy colour being obtained by the addition of a small amount of colouring matter to the pulp.
Featherweight papers are made entirely of esparto, very little sizing is added, no loading is used, the paper is treated so that the wire and felt marks are not easily visible, and the drying and finishing are carried out so as to retain the bulkiness of paper. It must always be remembered that all papers made under such conditions are not durable, and therefore should never be used for work which must withstand any considerable handling.
Coloured and tinted papers are made of the same materials as white printings, but usually the fibres will be chemical wood and esparto, all chemical, or a mixture of chemical and mechanical wood pulps. The variety of tints in which papers can be obtained is very extensive, and this is impressed upon one when trying to match up some particular shade, when it appears as though makers have many substitutes for the desired colour. The colours of papers should be fairly fast to light, and with the large variety obtainable by the use of the pigments and dyes now on the market, paper-makers manage to offer a long range of fast colours. Although it may not always be so, fastness usually follows the price of the paper, the cheapest being the most liable to fade quickly. Delicate tints are more expensive because of the necessity of a better quality of paper to take the colours evenly and cleanly. Coloured printing papers should be fairly well sized, well finished, and free from spots and specks.
In addition to possessing the good qualities of ​printings, lithographic papers must be firm and free from permanent stretch. In letterpress printing, only a portion of the paper is pressed by the printing surface, but in lithography the whole of the paper is brought into contact with the stone or other surface. If the printing surface is full or solid, as in the case of printing a ground tint, the pull on the surface of the paper is heavy, and unless the paper is well made the surface will pluck or pull up in patches, or even all over the sheet. The pressure exerts a stretching influence on the paper, and the moisture from damping induces expansion of the sheet. Lithographic papers require special care in selection of material and manufacture, so as to introduce and preserve all the necessary qualities of easy printing, perfect register, and quick drying.
Esparto fibre is short and soft, prints easily, and experience has proved that esparto papers stretch less than most other papers, and therefore litho papers usually contain a large proportion of this useful material. An all-rag litho. paper is the first quality; then rag and esparto, all esparto, chemical wood and esparto, mark the various grades of paper for lithographic printing. While the papers should not be hard-sized, they should not err on the other side, or absorption of moisture may cause trouble when registering. Soft materials, beaten quickly, dried gradually, not drawn too fast by the drying cylinders, are necessary to produce a satisfactory paper. The surface must be perfectly smooth, and this is obtained by super-calendering or plate-glazing, both of which tend to reduce the liability of the papers to stretch. The latter method is the better but more expensive method of producing the desired surface, and by turning the piles of paper and rolling in each direction of the sheet, subsequent stretch in working is reduced to a minimum.
​Plate papers are fine papers, soft-sized, lightly rolled, usually having one side only with a smooth finish. Thick plate papers are made by rolling two or more webs of wet paper together, and finishing as usual. The softness of the paper enables it to take all the ink from the finest lines of the steel or copper plates printed upon the surface.
Poster paper for lithographic or letterpress printing is made with a rough back to enable pasting to hoardings to take place more easily. These papers are made on the single cylinder machine, and, having only one side glazed—the printing side—are known as M.G. poster papers.
Imitation art papers are distinctly between super-calendered printings and art papers in printing quality, but they lack strength, owing to the method of their manufacture. Art paper has a mineral coating, while imitation art has a large percentage (about 25 per cent.) of china clay mixed with the pulp. China clay, having no cohesion, does not assist in felting the paper in any way, but tends to weaken its resistance to wear. That weakness or tenderness is one feature of imitation art papers. After leaving the paper machine the paper is super-calendered, receiving a water finish, that is, the paper is just wetted on the surface immediately before entering the rolls of the calender. The loading is thus brought to the surface, and a very smooth level sheet is produced, only a little inferior, as a printing surface, to art paper. Being opaque, suitable for half-tone printing, and of good appearance, imitation art is used largely for illustrated magazine work, and serves the purpose well, but it should be remembered that the large proportion of mineral matter renders the paper liable to disintegration from frequent handling.