How to Bleach Cellulosics Using Continuous Method
It is very important that the goods to be dyed are pre-scoured to be free of any processing chemical additives such as sizes, waxes, oils, peroxide, chlorine, or natural contaminates.
Bleaching is necessary if the desired dyeing is a light pastel shade or a very bright shade. This process may not be necessary for dull, earthtone, dark, navy, or black shades.
Do not exceed a pH of 9.0 when bleaching rayon as the rayon will begin to saponify.
- Saturate goods in bleach bath containing 1-3 % owb hydrogen peroxide 50%, 1.0 % owb sodium silicate, 0.2-0.6 % owb sodium hydroxide, and 0.25% owb Anionic Wetting Agent. pH should be about 10.5-11.0 for cotton.
- Pad goods and steam for 20 minutes to 1 ½ hours, depending on equipment and type of steam.
- Wash goods through two water baths; first at 160°F(71°C) for 15 seconds then 75°F(24°C) for 15 seconds.