Bleaching: In commercial bleaching the material to be bleached is first moistened with a very weak solution of sulphuric acid or hydrochloric acid, and is then immersed in the bleaching powder solution. As the moist material is drawn through the bleaching solution, the acid on the fabric acts upon the solution and releases chlorine. The chlorine liberates oxygen from the water. The oxygen in turn attacks the coloring matter and destroys it.
The bleached material is then immersed in a neutralizing bath and is finally rinsed thoroughly in water. Strips of cotton or linen many miles long are drawn by machinery into and out of the various solutions, are then passed over pressing rollers, and emerge snow white, ready to be dyed or to be used as white fabric.
FIG. - The material to be bleached is drawn through an acid a, then through a bleaching solution b, and finally through a neutralizing solution c.