Bleaching cotton with peroxide can affect the subsequent dyeing with reactive dyes. For this reason it is necessary to wash very well the material after bleaching, using a lot of water in the process. Reducing agents or enzymes that can be used to destroy the peroxide, or/and acid to neutralise the material. All these are however extra steps needed, which means time spent filling and emptying the machine and in the process itself, and extra water and energy. With bleaching after dyeing all these steps are avoided. For PE/CO blends the peroxide also clears the excess disperse dye substituting the reducing agent, hydrosulphite, which is very poluting. It also shortens the process since it does away with the intermediate rinsing.For these blends milder oxidants such as perborate can be used since whiteness of the cotton component is not so relevant, which means that a greater nunber of reactive dyes can be used.