The same natural dye can give different shades depending on the yarn, which they paint, the characteristics of local water, and used in the painting process additional reagents, including fixing. As a fixative used citric acid, caustic soda and other substances – they protect the paint from washing away, erase, and make it durable. Experienced painters are in the same way that artists mix paints on his palette – colors also mixed to give a wide range of colors and shades. The need for easy-to-use dye-wide color came from the Persian carpet in the middle of the 19th century. During this period, exports rose sharply in oriental rugs Western countries and the masters of Persia (Iran) and other centers of carpet Middle East have tried to keep up with demand. It was at this time on the market received the first aniline dyes. However, the aniline dyes were a major drawback: although they were bright and inexpensive compared with natural, they quickly faded when exposed to light and 'floating' on water. In 1903 Nasser-al-Din, shah of Persia from the Qajar dynasty forbade the use of aniline dyes.
Therefore, in nachel century in the manufacture of synthetic colors of Persian rugs were not used – until such time as the interval between the first and second world wars were not izbreteny chrome dyes. These dyes have high color retention (retain their color and brightness independently of exposure to sunlight and water), and produced in many variations of colors and shades. Now for yarn dyeing, going on manufacture of carpets, in most cases, used chrome dyes.