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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.
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]
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.
Batch dyeing (exhaust dyeing) is a method of dyeing a textile material. The method involves the gradual transfer of dye from a dye bath to the textile material in the same piece of equipment. [1] The various methods of batch dyeing result from the type of machine used in the dyeing process.
Vat dyes are a class of dyes that are classified as such because of the method by which they are applied. Vat dyeing is a process that refers to dyeing that takes place in a bucket or vat. The original vat dye is indigo , once obtained only from plants but now often produced synthetically.
Some dyestuffs, such as indigo and lichens, will give good color when used alone; these dyes are called direct dyes or substantive dyes. The majority of plant dyes, however, also require the use of a mordant, a chemical used to "fix" the color in the textile fibres. These dyes are called adjective dyes or "mordant dyes". By using different ...
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.
During the dyeing process, the dye must become close and even with the material in order to produce a uniform color that is fast to moisture, heat, and light. [5] Due to their superior fastness properties and simple application, reactive dyes are currently the most common type of dye for cotton dyeing. [6] The CPB technique uses less water and ...