There are three main types of natural dyes: plant pigments, animal pigments and minerals. Mineral pigments are mostly inorganic substances and are generally insoluble in water. They are usually used as pigments and only a few are used as dyes. Most of the natural dyes come from plants, mainly plant roots, stems, leaves, flowers, fruits, and a small amount from animals such as lac insects and cochineal insects. The colors of natural dyes are the most abundant in yellow and red, with less blue, green and black.
Natural red dye
Most red pigments are present in the plant's roots, bark, or dark gray insects. Although the source of the red pigment is limited, it is present in plants in large amounts and is easily extracted. Carmine is the most beautiful red pigment.
The ability of the grass to dye, was first discovered by Africans. They found that the grass was not only delicious, but its roots also dyed their lips red, and it was difficult to wash them off. Therefore, it was one of the earliest cosmetics. There are two main sources of valerian, valerian and British valerian. The root growth period of Pteris violaceum used to extract the dye should be two years or three years, when the root diameter is about 0.6cm and the length is about 60cm. Dig out the roots that meet the growing season, wash, and then dry them. Then put them in a thin cloth bag and add the water to boil. The red dye will be precipitated from the roots. Generally 2% of the dye is obtained from the dried root.
The pigment extracted from Pteris vittata is known as alizarin, and its main component is 1,2-dihydroxyanthraquinone. The yarrow can be used for direct dyeing. The valerian root is added to warm water at 30°C, and then the previously dyed wool fabric is added. The temperature of the dyeing solution slowly rises to 100°C, and the temperature drops immediately after dyeing for 1 to 1.5 hours. 90 °C, and then dyed at 90 °C for half an hour, stirring regularly, when the desired shade, the wool fabric in the dyeing solution after cooling, successively rinsed in warm water, water, dehydrated, Joan, about 120g hair The fabric requires 60 g of barnyardgrass and 4.51 L of water. On the cotton fabrics, valeraria complexes with mordants to form insoluble metal complex dyes, which are dyed bright red, commonly known as Turkish red.
Lac is a resinous protective secretion secreted by the lac insects. The gram insect is a parasite that grows on a large number of wild or plant species. The viscose shellac is dissolved with water and sodium carbonate solution, and then precipitated with lime to obtain the shellac dye, which is bright red and scarlet. In the production of water-soluble dye insect films, it is necessary to remove the useless color of the chromatin, and the extracted red dye often has dust. Therefore, it must be carefully filtered and removed before dyeing to prevent the dust from sticking to the dyed fabric during the dyeing process. During the dyeing process, the dye liquor is boiled first, and the cotton hank yarn is immersed in it for dyeing until the desired color is obtained. When dyeing, the process is the same, but the resulting color is usually deeper. If the cloth is boiled in sour bean leaves before dyeing, the resulting color fastness is better.
There are many natural red dyes, such as monascus pigments secreted by Monascus fungi, which are produced by Monascus erythraea and can dye silks into beautiful dark reds in acid baths below the isoelectric point. In addition, beet red pigment from red beets produced by yeast, as well as many red flowers (henna) can extract red pigment.
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