The French papers speak of a method of rendering paper extremely hard and tenacious, by subjecting the pulp to the action of chloride of zinc. After it has been treated with the chloride, it is submitted to a strong pressure, thereafter becoming as hard as wood and as tough as leather. The hardness varies according to the strength of the metallic solution. The material thus produced can be easily coloured. It may be employed in covering floors with advantage, may replace leather in the manufacture of coarse shoes, and is a good material for whip-handles, the mountings of saws, for buttons, combs, and other articles of various descriptions. An excellent use for it is large sheets of roofing. Paper already manufactured acquires the same consistency when plunged, unsized, into a solution of the chloride.
To prevent ink from adhering to and sinking into lithographic paper, which would render a perfect transfer to the stone impossible, the following plans are used: (1) Coat the paper with three successive layers of sheep-foot jelly, one of cold white starch, and one of gamboge. The first coat is applied by a sponge dipped in the hot solution of jelly, thinly but very evenly over the whole surface; the others are applied in succession, each previous one being allowed to dry first. When the paper is dry, it is smoothed by passing through the lithographic press. (2) Cover rather strong unsized paper with a varnish composed of 120 parts starch, 40 of gum-arabic, and 20 of alum. Make a moderate paste of the starch by boiling, dissolve the gum and alum separately, and then mix all together. When well mixed, apply hot with a flat smooth brush to the leaves of paper. Dry and smooth by passing under the press.
A luminous and damp-proof paper is prepared by adding phosphorescent powder and gelatine to the pulp. The proportions are: 10 parts water, 40 paper pulp, 20 phosphorescent powder (preferably slacked for 24 hours), 1 gelatine, 1 saturated solution potash bichromate. See also Luminous Substances, p. 380.
(1) Brush sheets of paper over with boiled oil in which a little shellac has been carefully dissolved over a slow fire; suspend on a line till dry. (2) The paper is laid on a square board, and well covered with a mixture composed as follows: boiled linseed-oil is reboiled with litharge, lead acetate, zinc sulphate, and burnt umber, 1 oz. of each per gal. The first sheet is covered on both sides, the second, placed on this, receives one coating, and so on; separate, and hang up to dry.
(1) Packing-paper may be made water-tight by dissolving 1.82 lb. of white soap in 1 qt. water, and dissolving in another qt. 1.82 oz. (apothecaries' weight) gum-arabic, and 5.5 oz. glue. The two solutions are mixed and warmed, the paper is soaked in the mixture, and passed between rollers or hung up to dry. (2) The paper is treated with boiled linseed-oil, the excess of oily particles being removed by benzene; it is then washed in a chlorine bath, and, after drying, treated with hydrogen peroxide. If the paper has been made from ropes, it is coated with a layer of starch before the treatment with linseed-oil and benzene. The final operation is " satining," by a passage through smooth rollers. (H) Russian oil-cask bottoms are often pasted over on the outside with a kind of paper having a gelatinous-looking skin, and which is quite oil-tight. Such has been brushed over with a mixture of blood and lime, a preparation much used in Russia and China, and quite oil-and water-tight. Chinese packing-cases are often pasted over with paper painted with this mixture. The Chinese schio-livo (see p. 72).is made by mixing 3 parts fresh blood (beaten up till free from fibrine) with 4 of dry powdery slaked lime and a little alum.
The thin pasty mass thus obtained may be used at once..
Paper which has been passed through a solution of glue with 5 per cent, potassium cyanate and antimony sulphide is immersed in a dilute solution of magnesium or copper sulphate, and afterwards dried. Nothing written on this paper with ink prepared from galls and iron salts can be destroyed by acids, etc, nor by mechanical erasing. Acids would colour the black writing blue or red, while alkalies would colour the paper brown; erasing would remove the surface of the paper, and show the white ground.
Lay the paper, face downwards, on a sheet of smooth unsized white paper; cover it with another sheet of the same, very slightly damped, and iron with a moderately warm flat-iron.
People who have not seen this done might think it impossible; yet it is not only possible, but extremely easy. Get a piece of plate-glass, and place on it a sheet of paper; then let the latter be thoroughly soaked. With care and a little dexterity, the sheet can be split by the top surface being removed. But the best plan is to paste a piece of cloth or very strong paper to each side of the sheet to be split. When dry, violently and without hesitation pull the two pieces asunder, when part of the sheet will be found to have adhered to one and part to the other. Soften the paste in water, and the pieces can be easily removed from the cloth. The process can be utilized in various ways. If it be wanted to paste in a scrap-book a newspaper article printed on both sides of the paper, and there is only one copy, it is very convenient to know how to detach the one side from the other. The paper when split, as may be imagined, is more transparent than before, and the printing-ink is somewhat duller.
Place cartridge or other paper on a hot iron and rub it with beeswax, or brush on a solution of wax in turpentine. On a large scale, it is prepared by opening a quire of paper flat upon a table, and rapidly ironing it with a very hot iron, against which is held a piece of wax, which, melting, runs down upon the paper and is absorbed by it. Any excess on the topmost layer readily penetrates to the lower ones. Such paper is useful for making waterproof and air proof tubes, and for general wrapping purposes.