WHITE OF YELLOW WAX. These spots yield promptly to pure turpentine, especially in a warm bath. When the spots thicken, they are lifted off with a scraper, or blotting paper may be applied, pressed down with a heated iron.
STEARINE. Wax tapers are today replaced by a kind of liquid grease, stearine, spots of which give paper a disagreeable transparency. These dissolve in warm alcohol or boiling water, but the spot remains stiff and the brilliance of the ink is reduced. The greater part of the stearine spot may be removed by the same process indicated for wax.
SEALING WAX. RESIN AND RESINOUS VARNISH. All dry resins yield to a warm alcohol bath. The thick part is removed as above. Sealing wax colored red, blue, etc., leaves a corresponding tint which is very tenacious.
TAR, PITCH, etc. These spots are rarely encountered. They give way to warm turpentine or cold benzine. If a dark trace remains, it sometimes may be removed by oxalic acid if the spot has not been burned by the hot tar. Whenever turpentine is used on any spots, it should always be the purest obtainable.
EGG YELLOW. This is always mixed with a little albumen, a matter which thickens in boiling water and can be drawn from the paper, along with the yellow. If the paper is smooth and well sized, all will disappear under a sponge in a bath of hot water. There sometimes remains a yellowish trace. To remove this, apply with a brush chlorated lime and then very weak hydrochloric acid.
MUD. This may be removed simply with a wet sponge or in a warm water bath. Where the paper is rough and absorbent, soap jelly should be used. If a dark trace remains, it usually will yield to oxalic acid or cream of tartar.
INK. Ordinary writing ink is easily decomposed because its principal constituent is a vegetable matter, oakgall, mixed with a little iron oxide. This gives way rather promptly to an application of sorrel salt dissolved in boiling water. The water must be boiling to secure prompt action. Even better success may be obtained by the use of pure oxalic acid, which is an extraction from sorrel salt of which it is the base.[8] Chinese ink cannot be dissolved but sometimes may be washed from a smooth page by means of a damp sponge. Marking ink may be removed with chloride of lime.
FRUIT JUICE. Stains from fruit may be removed by chlorine or cream of tartar. In some cases, water alone is sufficient.
BLOOD. These stains may be bleached by chloride of lime. As this must be applied for at least twenty minutes, it is better to use it as a damp paste. There will remain a yellow trace which will give way to a weak acid.
FECAL MATTERS OR URINE. For such spots, try soap and water. If this is unsuccessful try successively chlorine, alkalis, oxalic acid and hydrochloric acid, soaking the page for an hour in water between each operation.