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Textile bleaching is the act of taking greige, or natural textiles before they are processed, and applying either oxidative or reductive bleach to the material. This is done for several reasons, such as removing pesticides and fungicides and making the textile softer. Depending on whether the textile is synthetic or natural, one of two bleach types are added to the material. After textile bleaching, optical whiteners are added to enhance the white color and to make the material easier to dye. Scouring is done beforehand to remove some of the textile additives and to make the textile absorbent.
When a textile is grown or made, it encounters many add-ons that make the textile easier to construct or keep insects or fungus from ruining the material. A few of these additives are fungicides, pesticides, lubricants and worm killers. While these add-ons are considered necessary during the growing or creation phase, they tend to be poisonous and can be harmful to consumers. While removing the poison, textile bleaching also makes the textile white, rather than the natural brown color of most textiles, and easier to dye.
If a textile is natural, such as cotton or wool, it is bleached with oxidative bleach. This strips the textile of the additives and destroys chromophores, the molecular elements that add color to the textile. Oxidative bleach pushes oxygen into the textile to perform this task.
Synthetic materials, such as polyacetate and polyacrylic, are treated with reductive bleach. In this textile bleaching method, the reductive bleach reduces the amount of oxygen in the textile. While the opposite of oxidative bleaching, reductive bleach performs the same task.
Cleansing the fiber and destroying the natural color are not the only reasons textile bleaching is performed. Another reason is that greige material is tough and generally considered difficult to work with and wear. By bleaching the textile, it breaks down the greige, making it softer and more comfortable.
In textile processing, textile bleaching is the second step of the procedure. Before bleaching comes scouring, in which wetting agents remove some of the additives; this is mostly done to make the textile water-absorbent. After bleaching, optical whiteners are added to the material. Much like bleach, this makes the textile whiter, but this step is only concerned with eradicating any color from the natural fiber so it can be sold as a white fabric or go on to dyeing.