Dyes for fabrics

In 1856, the English chemist William Perkin persevered in experiments to obtain quinine, but instead he discovered one of the first artificial colors, Mowein. From this time, artificial colors for the fabric originate.

In 1882, German chemist Adolf Bayer established the structure of indigo and received it by artificial means. He has been particularly in demand recently as the best dye for denim fabrics

Until then, people used only natural dyes for tissue. Kampeshevo wood and roots of the madder, acacia juice and blueberries, saffron flowers and reseda - that was the source of the dyes.

The history of indigo, the "king" of dyes for tissue, is rich in events. Since ancient times, it was extracted from the stems and leaves of an indigo plant growing in the tropical countries of Asia. In 1882, German chemist Adolf Bayer established the structure of indigo and received it by artificial means. He has been particularly in demand recently as the best dye for denim fabrics.

In a relatively short time, synthetic dyes for tissue almost completely replaced natural dyes. The main raw material for the production of dyes is the products of oil refining and coking of coal.

In order to color the skin, complex pre-treatment is needed. First, the skin is kept for several days in a solution of lime in a mixture with sodium sulfide to remove the hair covering. After that, the special composition is made by its de-mineralizing and softening. Then the skin is tanned, so that it becomes firm and plastic, has got water repellent and antiseptic properties. Only after that the skin is painted in the right color.

The process of dyeing anodized aluminum products is very interesting. First, an electric circuit is assembled, in which the aluminum plate to be painted serves as an anode. The anode and the cathode are lowered into dilute sulfuric acid and electric current starts to flow through a certain strength. At the same time, an oxide film is formed on the surface of aluminum, which is easily colored with dyes.

For different fabrics, different dyes are needed: some color the wool, others - cotton fabrics, the third - fabrics from various synthetic fibers. But to all these dyes the same requirement is made - to give coloring not only beautiful, but also durable. It should not burn out in the sun and deteriorate when ironing the fabric with an iron, shedding while washing and leaving traces of rubbing on white fabric. Hence, the dye must be firmly connected with the cloth. Most dyes are retained on the tissue due to the forces of attraction between their molecules and the fibers of the tissue. A much stronger color is given by active dyes. In their molecules there is an active group, which splits off during dyeing. There is a strong chemical bond between the dye and the fiber of the tissue.

Along with colored dyes, white fabrics and white paper are needed. To make white materials even more whiteness, optical brighteners, or white whiteners, are used. In their structure, these are ordinary dyes. But their molecules have a very interesting property - the treatment of white material with an optical bleach prevents the appearance of an unpleasant yellow shade.

Woolen and cotton fabrics, it turns out, have the worst enemies. These are different microorganisms, molds and bacteria. If they get on the cloth, they can multiply quickly, making the fabric go out of order - rotting, losing strength. This process of great harm, similar to the corrosion of metals, is called biological corrosion. To protect against biological corrosion, it is convenient to use dyes for tissue that have bioprotective properties.

And what has become of natural dyes? Natural dyes are used in the food industry. Since they are absolutely harmless to humans, they tint the shells for cheeses, confectionery, liqueurs and fruit waters.