When just enough alkali is used to completely saponify the amount of fat, the product is called a neutral, or mild, soap. When an excess of alkali is present, the soap is termed medium or strong, according to the amount of free alkali it contains.
A mild soap should be used when free alkali would be injurious, as in washing woollens or fabrics that have delicate colours.
4. Soap substitutes, or adjuncts:
(1) Use.—To act alone or with soap in exerting a solvent action on greasy impurities, so that the cleansing process may be facilitated.
(2) Kinds:
(a) Alkalies.—These must be used in excess of the amount needed for softening the water.
(b) Harmless solvents, such as turpentine, paraffin, coal-oil, gasolene.—The clothing must be well rinsed to get rid of any odour.
(c) Washing powders.—These are prepared mixtures of soap and some other solvent of greasy matter.
5. Blueing:
(1) Use.—To make clothes which have a yellow tinge appear whiter in colour.
(2) Kinds.—There are several kinds on the market, but the names of these will be of no value to the class.
Note.—Sufficient blueing should be used to make the blueing water a pale sky-blue colour when a little of it is lifted in the hand.