Page 92 - Shawl Weaving Artisan - TP

9 Then prepare a new bath with clean water and add a 12 Gently squeeze out excess water without wringing
small amount of acetic acid to adjust the pH to 6-7. (wringing can damage wool fibers).
10 Soak the yarn in this neutralizing bath for 15 minutes. 13 Lay the yarn flat or hang it in a shaded, well-ventilated
area to air dry.
11 Rinse the yarn again with clean water to remove any
remaining chemicals.

TASK 2: Bleaching of cotton yarn with sodium chlorite

1 Heat water to 90–95°C in a container. 8 Heat the solution to 80–90°C and keep the yarn in it
2 Add caustic soda (NaOH) in it. for 1–2 hours.
9 Stir occasionally to ensure uniform bleaching.
3 Then add 1–2 g/l, detergent in a solution.
10 Then check the yarn for the desired whiteness level.
4 Soak the cotton yarn in this solution for 45–60 If achieved, move to the next step.
minutes and stir gently.
5 Rinse well with warm water to remove all chemicals. 11 Drain the bleaching bath and rinse the yarn with
Luke warm water.
6 Then prepare a bleaching bath:
12 Then prepare a neutralizing bath:
• Fill a clean container with warm water 70–80°C.
• Add 1–2 g/L sodium bisulfite (NaHSO ) to fresh
• Then add sodium chlorite (NaClO ), 3–5 g/l and water. 3
2
stir well.
• Soak the yarn in this bath for 15 minutes to
• Now add the formic acid for adjusting the pH to remove chlorine dioxide residues.
3.5–4.5.
13 Rinse again with clean water.
7 Then immerse the scoured cotton yarn in the 14 Gently squeeze out excess water (do not wring).
bleaching bath.
15 Air-dry in a shaded, well-ventilated area to avoid
fiber damage.

80 Textile & Handloom : Shawl Weaving Artisan (NSQF - 2024) Exercise 1.6.54