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Substantive dyes work best on textiles with high contents of cellulose, such as cotton. In contrast to direct dyes, wool and leather goods are dyed by the process of ion exchange, exploiting the cationic nature of proteins near neutral pH. The development of substantive dyes helped make mordant dyes obsolete. [2]
Also called direct dyes, substantive dyes are employed for cellulose-based textiles, which includes cotton. The dyes bind to the textile by non-electrostatic forces. In another classification, azo dyes can be classified according to the number of azo groups. Trypan blue is an example of a direct dye, used for cotton.
Direct or substantive dyeing is normally carried out in a neutral or slightly alkaline dye bath, at or near boiling point, with the addition of either sodium chloride (NaCl) or sodium sulfate (Na 2 SO 4) or sodium carbonate (Na 2 CO 3). Direct dyes are used on cotton, paper, leather, wool, silk and nylon.
Natural dyes are dyes or colorants derived from plants, invertebrates, or minerals. The majority of natural dyes are vegetable dyes from plant sources—roots, berries, bark, leaves, and wood—and other biological sources such as fungi. [1] Archaeologists have found evidence of textile dyeing dating back to the Neolithic period.
Mordant red 19 is a typical mordant dye. Like many mordant dyes, it features the azo group (RN=NR) and various sites for chelating to metal cations. A French Indienne, a printed or painted textile in the manner of Indian productions, which used mordants to fix the dyes. A mordant or dye fixative is a substance used to set (i.e., bind) dyes on
The like charges repel each other, and the addition of salt aids in dyeing by generating a positive charge on the cotton surface. [7] [8] The industry has predominantly used reactive dyes to color knitted cotton goods. The treatment of salt-laden, colored effluent generated by the dyeing process is one of the industry's primary concerns. Cotton ...
Direct blue 218 Direct blue 218 24401 diazo 28407-37-6: Direct brown 2 Direct brown 2 22311 diazo 2429-82-5: Direct sky blue 5B Direct sky blue FB Direct Blue 15: 22400 diazo 2429-74-5: Direct sky blue 6B Direct sky blue FF Direct Blue 1: 24410 diazo 2610-05-1: Direct yellow 4 Brilliant fast yellow Direct yellow 4 24890 diazo 3051-11-4: Direct ...
The common dyeing process of cotton yarn with reactive dyes at package form is as follows: The raw yarn is wound on a spring tube to achieve a package suitable for dye penetration. These softened packages are loaded on a dyeing carrier's spindle one on another. The packages are pressed up to a desired height to achieve suitable density of packing.