Paper coated with glass is known by this name just as paper coated with fine sharp sand is called sandpaper, and paper coated with emery is called emery paper. Paper or a cheap cloth is coated with thinnish glue, dusted heavily and evenly with glass-powder of the proper fineness, and allowed to become nearly dry. The superfluous powder is then shaken off, the sheets are pressed to make them even, and afterwards thoroughly dried.
The objection to ordinary glass-paper is that it is easily injured by heat and moisture. If the glue be mixed with a little bichromate of potassa before it is applied to the cloth, and exposed for some time to strong bright sunshine while it is drying, it will become insoluble in water.
The glue may also be rendered insoluble by the process of tanning. The paper or cloth is first soaked in a solution of tannic acid and dried. The glue is then applied, the powdered glass dusted on, and over it is dusted a little tannic acid. If the glue be not very moist, it should be damped by means of an atomiser, a very cheap form of which is figured in The Young Scientist, vol. 2. The sheets are then slowly dried and will be found to resist moisture very thoroughly.
To prevent the absorption of varnish, and injury to any color or design on the paper, it is necessary to first give it two or three coats of size. The best size for white or delicate colors is made by dissolving a little isinglass in boiling water, or by boiling some clean parchment cuttings until they form a clear solution; then strain through a piece of clean muslin. It may be applied with a clean soft paint brush, the first coat, especially, very lightly. The best brush for this purpose is the kind used by varnishers for giving the finishing flow coats of varnish, wide, flat and soft; or where there is much danger of injuring a design, and the paper article will allow of it, it is a good plan for the first coat, to pour the solution into a wide, flat dish, and pass the paper through it once, and back again, and then hang it up to dry. For less delicate purposes, a little light-colored glue, soaked over night in enough water to cover it, and then dissolved by heat, adding hot water enough to dilute it sufficiently, will make an excellent sizing.
Boil white paper or paper cuttings in water for five hours. Pour off the water, pound the pulp in a wedgwood mortar, and pass through a fine sieve. This powder is employed by the bird stuffers to dust over the legs of some birds, and the bills of others, to give them a powdery appearance; also to communicate the downy bloom to rough-coated artificial fruit, and other purposes of a similar nature; it makes excellent pounce.
Tracing paper may be purchased so cheaply that it is hardly worth while to make it; and there is a very fine, tough kind now in market which may be mounted and colored almost like drawing paper. Those who desire to prepare some for themselves will find that the following directions give a good result. The inventor of the process received a medal and premium from the Society of Arts for it.
Open a quire of tough tissue paper, and brush the first sheet with a mixture of equal parts of mastic varnish and oil of turpentine. Proceed with each sheet similarly and dry them on lines by hanging them up singly. As the process goes on, the under sheets absorb a portion of the varnish, and require less than if single sheets were brushed separately. The paper, when dry, is quite light and transparent, and may readily be written on with ink.
This is useful for copying patterns, drawings, etc. Designs for scroll saws may be copied very neatly by means of it. It is easily made by rubbing a thin but tough unglazed paper with a mixture of lard and lampblack. The copy is made by laying a sheet of the transfer or, as it is sometimes called, manifold paper, over a clean sheet of drawing or writing paper, and over it the drawing to be copied. The lines of the drawing are then carefully traced with a fine but blunt point, and the pressure along the lines transfers to the clean paper underneath a perfect copy. To keep the under side of the drawing or pattern clean, a sheet of tissue paper may be placed between it and the transfer paper.
Fill a large vessel with pure water and dip the engraving in, waving it backward and forward until thoroughly wet. Then spread a sheet of clean white paper on a drawing board, lay the engraving on it and fasten both to the board with drawing pins. Expose it to bright sunshine, keeping it moist until the stains disappear, which will not be long. This is simply a modification of the old system of bleaching linen.
Paper saturated with wax, paraffin or stearin is very useful for wrapping up articles which should be kept dry and not exposed to the air. Place a sheet of stout paper on a heated iron plate, and over this place the sheets of unglazed paper - tissue paper does very well - that are to be waxed. Enclose the wax or paraffin in a piece of muslin, and as it melts spread it evenly over the paper.