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A "vital dye" or stain is a dye capable of penetrating living cells or tissues without causing immediate visible degenerative changes. [26] Such dyes are useful in medical and pathological fields in order to selectively color certain structures (such as cells) in order to distinguish them from surrounding tissue and thus make them more visible ...
In natural dyeing, there are "fast" dye compounds (those that have the necessary molecular structure to form stable chemical bonds with mordants and fibres, and so provide good resistance to fading when washed, exposed to light, or subjected to normal rubbing/abrasion; these are found throughout the historic record), and there are "fugitive ...
Dyeing Pigments for sale at a market in Goa, India Cotton being dyed manually in contemporary India Silk dye in pan on stove. Khotan. Dyeing is the application of dyes or pigments on textile materials such as fibers, yarns, and fabrics with the goal of achieving color with desired color fastness.
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]
“It’s important that the dye is biocompatible – it’s safe for living organisms,” Ou said. “In addition, it’s very inexpensive and efficient; we don’t need very much of it to work.”
Scouring removes soluble and insoluble impurities found in textiles as natural, added and adventitious impurities: for example, oils, waxes, fats, vegetable matter, as well as dirt. Removing these contaminants through scouring prepares the textiles for subsequent processes such as bleaching and dyeing . [ 1 ]
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.
Dye results can also rely on the mordant chosen as the introduction of the mordant into the dye will have a marked effect on the final color. Each dye can have different reactions to each mordant. For example, cochineal scarlet, or Dutch scarlet as it came to be known, used cochineal along with a tin mordant to create a brilliant orange-hued ...