A Practical shop-floor down to earth tips on Vat Dyeing.

Page-8

OXIDATION METHODS FOR BLACK BB AND BLACK NB POWDER

1. Oxidation with 2 to 4 g/l of Hydrogen peroxide at 50'c for one hour at pH 10.5 to 11.5.

• wash cold with water

• No acidification with acetic acid

    2.   Oxidation with Sodium Hypo Chlorite.

• Black NB will yield an olive shade after Hydrogen Peroxide oxidation. To achieve jet black shade, the yarn or fabric is treated in an alkaline bath at 10.5 pH with 4 gms/liter of Sodium Hypo Chlorite solution at cold for 1 hour.

•  Cold wash in running water for 14 minutes.

• Neutralize with Neutra-fab (Rossarre)  - 2 g/l at cold for 15 minutes, cold wash for 15 minutes.

• Neutralize with Acetic acid - 1 ml per liter at cold for 20 minutes.

   3.    Soaping:

• Soda ash   - 2 g/l

• Lissopol D paste - 2 g/l    - do soaping at 95'c for 30 minutes.

• Hot Wash at 75'C for 30 minutes

• Cold Wash for 10 minutes

Finally treat the fabric with acetic acid 1 g/liter at cold for 10 minutes. Check the pH to 6 and dry the fabric.

[Previous page]