The following process will restore the original whiteness of copper-plate, wood-engraving or printed matter:—Place a piece of phosphorus in a large glass vessel; pour in water of 30° centigrade (that is 86° Fahrenheit) temperature until the phosphorus is half covered. Cork up, but not tightly, the glass vessel, and lay it in a moderately warm place for fourteen hours. Damp the paper that is to be bleached, with distilled water; fasten it to a piece of platinum wire and hang it up inside the glass vessel. The faded paper after a short time will regain its original white color. It should then be taken out and washed in water; next drawn through a weak solution of soda, and finally dipped in pure water and laid on a glass table, and thus made dry and smooth.
For Electrotyping on China.
For electrotyping on China and similar non-conducting materials:—Sulphur is dissolved in oil of spike lavender to a syrupy consistence; then chloride of gold or chloride of platinum is dissolved in ether, and the two solutions mixed under a gentle heat. The compound is next evaporated until the thickness of ordinary paint, in which condition it is applied with a brush to such portions of the china, glass or other fabric as it is desired to cover, according to the design or pattern, with the electrometallic deposit. The objects are baked in the usual way before they are immersed in the bath.
Painting on Ebonized Wood.
The great difficulty to be overcome in painting on ebonized wood, is the non-absorbent character of the surface, which will not allow the paint to sink in. Washing the panel over with onion juice enables the paint to adhere more easily. The paint, whether oil or water color, must be laid on thickly. In order that the painting, whether of flowers or figures, shall prove a decoration, the black space between the painted figures must be graceful in shape. Water color paintings on such panels require to be varnished. Oil color does not need the varnish.
How Gilding is Done.
Letters written on vellum or paper are gilded in three ways. In the first a little size is mixed with the ink, and the letters are written as usual; when they are dry a slight degree of stickiness is produced by breathing on them, upon which the gold leaf is immediately applied, and by a little pressure may be made to adhere with sufficient firmness. In the second method some white lead or chalk is ground up with strong size, and the letters are made with this by means of a brush; when the mixture is almost dry, the gold leaf may be laid on and afterward burnished. The best method is to mix up some gold powder with size, and make the letters of this by means of a brush.
The edges of the leaves of books are gilded while in the binders’ press, by first applying a composition formed of four parts of Armenian bole and one of sugar candy, ground together to a proper consistence; it is laid on by a brush with white of egg; this coating, when nearly dry, is smoothed by the burnisher; it is then slightly moistened with clear water, the gold leaf applied, and afterwards burnished.
In order to impress the gilt figures on the leather covers of books, the leather is first dusted over with very fine powdered resin or mastic; then the iron tool by which the figure is made is moderately heated and pressed down upon a piece of leaf gold which slightly adheres to it, being then immediately applied to the surface of the leather with a certain force; the tool at the same time makes an impression, and melts the mastic which lies between the heated iron and the leather; in consequence of this, the gold with which the face of the tool is covered is made to adhere to the leather, so that on removing the tool a gilded impression of it remains behind.