3.2. Test on presence of an optical bleach
Equipment. Ultra-violet lighter УИ- 1 or any other device giving only ultra-violet radiation.
Reactants. Strips of a white cotton fabric or a filtering paper. Analysis carrying out. Strips of a white cotton fabric or a filtering paper consider in the dark at ultra-violet illumination. Absence of fluorescence testifies that on them there is no optical bleach.
Then prepare 0,5 % solution of a synthetic detergent powder, immerse in it a strip of a cotton fabric or a filtering paper and consider in the dark at ultra-violet illumination. Fluorescence occurrence testifies to presence OOS in a powder.
4. Dyeing
The dyeing of cloth is an ancient art. In 1856 William Henry Perkin accidentally discovered the first synthetic dye while trying to synthesize quinine from allyltoluidine. Instead of quinine he produced a purple solution which proved to be a good dye for fabrics. The purple dye came to be known as Perkins Mauve, and Perkin went on to found the British coal tar dye industry.
The founding of the first dye company is considered the birth of the organic chemical industry.
Although numerous colored compounds and, thus, potential dyes have been produced since the 1850s, the successful dyeing of a cloth sample depends both on the structure of the fibers in the cloth and the structure of the dye.
4.1. Technical classification of dyes
1. Water-soluble dyes
1.1 Water-soluble dyes anionic type
1.1.1. Acid dyes
1.1.2. Mordant dyes
1.1.3. Acid metalline dyes
1.1.4. Direct dyes
1.1.5. Reactive dyes
1.2. Water-soluble dyes cationic type
1.2.1. Cationic dyes
2. Water insoluble dyes
2.1. Vat dyes
2.2. Sulfur dyes
2.3. Disperse dyes
2.4. Pigments
3. Water-soluble forms of water insoluble dyes
3.1. Water-soluble forms of vat dyes
3.2. Water-soluble forms of sulfur dyes
4. Azo dyes synthesized in the fiber
In order to dye the various types of fibers, numerous methods have been developed. Dyes have come to be classified according to the dyeing method most commonly employed in their use. These classifications are: direct dyes, disazo dyes, ingrain or developed dyes, mordant dyes, vat dyes, fiber reactive, disperse dyes, and optical brighteners. Some dyes fall into more than one of the above classifications; dyes are sometimes also classified according to their structural class, e.g., azo, triphenyl-methane, anthraquinone, etc.
4.2. Acid dyes
Acid dyes are used mainly for dyeing wool at all stages of it treatment, however, they can be applied with a success for polyamide fiber and natural silk.
An acid dye forms a strong ionic bond with the fabric in acid presence:
Booklet introduces a customer with a range of acid dyes, methods of its applications and color fastness to different physico-chemical influences.
Two names of reactive dyes with mark "Sh", which are used as acid ones are included in the booklet.
Dyeing of wool by acid dyes
1. Dyeing from neutral bath, % (pH=5,5-6,5) for bad leveling dyes
Dye. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . X
Glauber salt. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Ammonium sulfate or ammonium acetate. . . . 3-5
Acetic acid (30%). . . . . . . . . . . . . . . . . . . . . . . . . 3-5
Water. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Y
2. Dyeing from weakly acid bath, % (pH=4-5) for middle leveling dyes
Dye. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .X
Glauber salt. . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Acetic acid (30%). . . . . . . . . . . . . . . . . . . . . . . .3-5
Sulfuric acid (density = 1,84) . . . . . . . . . . . . .1-2
Water. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Y
3. Dyeing from acid bath, % (pH=2,5-3,5) for well leveling dyes
Dye. . . . . . . . . . . . . . . . . . . . . . . .X
Glauber salt . . . . . . . . . . . . . . . . 10
Sulfuric acid (density = 1,84) . . 2-4
Water. . . . . . . . . . . . . . . . . . . . . . Y
Fig. 4.1. Procedure of М 1:20
A - glauber salt, ammonium salt, acetic acid, В - solution of dye, С - acetic or sulfuric acid
After dyeing washing out is followed in warm and cold running water.