Saminathan Ratnapandian

Chemical
Concentration (g/l)
Caspian (A. nilotica) or Thar (A. catechu)	10
Chitosan (w/v %)	0.025/0.05/0.075/0.1
Potassium sulfate	1

Cotton fabric (10 g) was padded using the 3 dip–3 nip technique at room temperature with 80% wet pick-up. As shown in Figure 5.2, curing or dry-baking at 130^○C instead of steaming was adopted for the fixation of chitosan [183]. Post-mordanting (dye padding followed by mordant padding) was followed throughout the investigation.
After padding with mordant, samples were cured at 100^○C for 5 minutes. The next step was soaping off with 1 g/l anionic soap solution at boil for 20 minutes. The samples were finally rinsed in hot and cold water respectively and dried at 65°C.
Curing at 130°C _{Curing at 100°C}


5 minutes 5 minutes


Time
Figure 5.2 Line diagram of pad dyeing in the presence of chitosan

2. Evaluation

Procedures described in Section 2.2.3 were followed to measure the colour strength and fastness properties of conditioned dyed fabrics. In addition, the antimicrobial effectiveness was assessed according to the procedure given in Section 2.2.3.3. The dyes, in solution by themselves, were also evaluated to eliminate the possibility of inherent antimicrobial properties that may be attributed to some polyphenols [115].

5. Results and discussion

   1. Shades obtained

The results were similar to those obtained previously for both Caspian and Thar dyes. Mordanting with copper (II) sulfate resulted in a beige shade while iron (II) sulfate yielded a grey shade, irrespective of the inclusion of chitosan. This is evident from the near-parallel reflectance curves (Figure 5.3 and Figure 5.4) for the two dyes. The lower curves obtained for the samples dyed in the presence of chitosan indicate a darker shade.
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