Three types of laundry bluing are in common use, namely, ultramarine, Prussian, and aniline blues. Since they differ chemically, spots due to them require different treatment. It is not difficult to determine to which type a blue belongs, and methods for doing this are suggested in the following paragraphs:

The commercial blues which come in balls or blocks with directions to wrap them in a piece of flannel or other cloth and shake them about in the water to be blued are generally ultramarine. To remove such stains, the following procedure may be followed:

1. Cold water. Soak fresh stains or rinse them in an abundance of cold water.

2. Soap and water. Wash the stains as in ordinary laundering, with an abundance of soap, and rub thoroughly. This treatment will remove stains which are not removed by soaking.

Liquid bluing, which is used commonly in the home laundry, usually is a Prussian blue. It is greenish-blue in color and soluble in water. Clothes are occasionally overblued with Prussian, as with other bluings, or may become streaked with the bluing if it has not been mixed evenly with the water. To overcome this condition the following treatment is recommended:

1. Cold water. Rinse the stains in an abundance of cold water. This is effective only for very fresh stains.

2. Boiling water. Boil the stained material for about half an hour, or until the stains disappear.

Prussian blue is sometimes the cause of yellow discolorations or spots upon white clothes. If the clothes are not rinsed free from strong soap, washing-soda, or other alkali used in washing, before they are blued with Prussian blue, the alkali remaining on the clothes precipitates ferric hydroxide from the bluing which is deposited upon the clothes. This is set by subsequent drying and ironing, and is identical, chemically, with iron-rust. For methods of removing these stains, see " iron rust" stains, page 297.

The aniline or coal-tar blues probably are used less commonly in the household than the other blues, but are employed frequently in commercial laundries. They are sold usually in the form of small crystals or of a powder having a dark blue or iridescent color and are soluble in water. To remove aniline blues, one of the following methods should be used:

1. Cold water. Soak the stained material for several hours or overnight.

2. Boiling water. Boil the stains for 15 minutes or until they disappear.