360. Methods of Removing Various Stains

360.    Methods of Removing Various Stains. Fruit-stains, wine-stains, and those made by colored vegetable juices, are often near-ly indelible, and require various treatment. Thorough rubbing with soap and soft water; repeated dipping in sour butter-milk, and drying in the sun; rubbing on a thick mixture of starch and cold water, and exposing long to sun and air, are among the expedients resorted to. Sulphurous acid is often employed to bleach out colors. It may be generated at the moment of using, by burning a small piece of sulphur in the air, under the wide end of a small paper funnel, whose upper orifice is applied near the cloth. Coffee and chocolate stains require careful soaping and washing with water at 120°, followed by sulphuration. If discoloration has been pro. duced by acids, water of ammonia should be applied; if spots have been made by alkaline substances, moderately strong vinegar may be applied; if upon a delicate article, the vinegar should be decolorized by filtering through powdered charcoal.

361. The Effects of Acids and Alkalies upon Different Colors

361.    The Effects of Acids and Alkalies upon Different Colors. The effect of acids upon blacks, purples, blues (except those produced by indigo or Prussian blue), and upon all those shades of colors which are produced by means of iron, archil, and astringent substances, is to turn them red. They render yellows more pale, except those produced by annotto, which they turn to an orange color.

Alkalies turn scarlets, and all reds produced by Brazil or logwood, to a violet color; they turn green (upon woolen cloths) to yellow, and they give a reddish cast to the yellow produced by annotto. The effect of the perspiration is the same as that of the alkalies.

Spots occasioned by acids are removed by alkalies, and vice versa. (See last receipt.)

362. To Restore Colors that have been Injured by the use of Re-Agents

362.    To Restore Colors that have been Injured by the use of Re-Agents. The colors of cloths are often injured by the re-agents made use of in order to restore them effectively; when such is the case we must not only understand the general principles of the art of dyeing, but the nature and composition of the particular dye that was originally employed for dyeing the cloth whose color is to be restored, and thus enabled to modify the means accordingly. Thus, when, after using an alkali to remove an acid spot upon brown, violet, or blue cloth, etc., there remains a

.. yellow spot, the original color is again produced by means of a solution of tin. A solution of the sulphate of iron restores the color to those brown cloths which have been dyed with galls. Acids give to yellow cloths which have been rendered dull or brown by alkalies, their original brightness. When black cloths dyed with logwood have any reddish spots occasioned by acids, alkalies turn such spots to a yellow color, and a little of the astringent principle makes them black again. A solution of 1 part of indigo in 4 parts of sulphuric acid, properly diluted with water, may be successfully employed to restore a faded blue color upon wool or cotton. Red or scarlet colors may be restored by means of cochineal, and a solution of muriate of tin, etc.. (See No. 113 (Tin Spirits).)