The document discusses the dyeing of cotton with vat dyes. It describes the general properties of vat dyes, including being insoluble in water and requiring reduction to a water-soluble form prior to dyeing. The document outlines the four main steps of vat dyeing cotton: reduction of the insoluble dye to soluble form, dyeing the cotton, oxidizing the dye inside the fiber, and soaping for brightness and fastness. It provides details on exhaust and continuous/semi-continuous dyeing methods.