With some stains prompt treatment is necessary in order to save the article in question from being ruined, and in most cases it is desirable, since all stains are removed more easily when fresh. Changes in the character of the stain, brought about by drying, exposure to air, washing, ironing, or in other ways, often make it necessary to use chemicals in removing old stains, whereas in many cases much simpler methods are successful if the stains are treated when fresh.

The nature of a stain should be known, if possible, before its removal is attempted, since this determines the treatment to be adopted. Moreover, if an unsuitable stain-remover is used, the stain may be "set" so that its removal becomes difficult or even impossible. For example, if hot water, which easily removes most fresh fruit stains, is applied to stains containing protein, such as stains of milk, blood, eggs, or meat juice, it coagulates the albumin in the fibers of the cloth and makes it extremely difficult to remove. Similarly, soap, which aids in the removal of grease spots, sets many fruit stains.

The kind of fabric upon which the stain occurs also should be known. The method of treatment adopted depends as much on the nature, color, weave, finish, and weight of the fabric as on the kind of stain. Cotton and linen are destroyed by strong acids and attacked to some extent even by weaker ones. Concentrated acids, therefore, should never be used in removing stains from these fabrics, and when dilute acids are used they should be neutralized afterwards with a suitable alkali or removed by thorough rinsing; otherwise the acid may become concentrated on drying and destroy the fibers. Generally speaking, alkalis do not attack cotton or linen fabrics to the extent that acids do. However, long-continued or repeated exposure to alkalis, especially in hot solution, weakens the fibers. The damage to fabrics resulting from the careless use of strongly alkaline soaps, washing powders, washing-soda, or lye, is well known to the housekeeper.

* This chapter contains almost the whole of Farmers' Bull. 861, Removal of Stains from Clothing and Other Textiles, by Harold L. Lang and Anna H. Whittelsey of the U. S. Dept. of Agr. Since this bulletin is the report of the most extensive and careful work on stain removal that has been done for the benefit of housekeepers, it has been only slightly adapted for reprinting here.

Wool and silk, being more delicate than cotton and linen, require more careful treatment. The use of very hot water must be avoided, since it turns both wool and silk yellow, shrinks wool, and weakens silk and injures its finish. These materials also will not stand much rubbing, as this felts together the wool fibers and results in a shrinking or thickening of the material, while the silk fabrics, as a rule, are too delicate to stand much rubbing without breaking or separating the fibers. Both wool and silk are dissolved by strong alkalis and are injured even by washing-soda or strongly alkaline soap. The only alkalis which should be used in laundering or removing stains from wool and silk are the milder ones like borax or dilute solutions of ammonia. Acids, with the exception of nitric which weakens and turns the fibers yellow, do not attack wool and silk readily.

In general it is more difficult to remove stains from wool and silk than from cotton or linen. In removing stains from materials made from two or more kinds of fibers, such as silk and cotton mixtures, the effects of the stain-removers on all of the fibers should be considered. No chemical should be used which would injure the most delicate of the fibers present.

It is also much more difficult to remove stains from colored than from white materials, for the reason that most of the bleaching agents which must be used to remove persistent stains are likely to destroy the color of the material as well.