The reason is that the traditional detergent can not effectively inhibit the process of dirt from washing clothes to redeposition of washing water on the washed clothes. After repeated washing with traditional detergents, the original soft texture of textiles will gradually disappear and be replaced by a hard and uncomfortable feel. This is the phenomenon of textile crust hardening in the world. Old towels that have been used for a long time are typical of this phenomenon. The reason lies in the consequences of using sodium tripolyphosphate and sodium carbonate as builders and kaolin and activated clay as fillers in traditional detergents. One of the important functions of sodium tripolyphosphate in traditional detergents is to combine with calcium hard ions in water, so as to precipitate the generated calcium phosphate from washing water and soften the water quality, thus protecting the decontamination effect of sodium alkylbenzene sulfonate, the main detergent decontamination component. However, calcium phosphate crystals precipitated from washing water will not only be deposited in washing water and washing tanks, but also in the outer surfaces and internal pores of clothes and textile fibers. After repeated washing and deposition, the texture of clothes and textiles will become hard. An important function of sodium carbonate in traditional detergents is to convert calcium hard ions in water into calcium carbonate and precipitate it from washing water. Of course, these hard calcium carbonate scales will also be deposited on the surface of clothing and textile fibers and the pores of the fibers, which will lead to the hardening of clothing and textiles and the loss of their original soft quality.