2.2.4. Dyeing rate
The cationised cotton fabric samples were cut into pieces
approximately 1 cm2 and dyed at pH 2.5 in a beaker with
160 ml aqueous solution composed of 1 g/l non-ionic wetting
agent (Hostapal CV, Clariant) and 8 g/l lac dye with liquor ratio
40:1 at 80 C with frequent shaking. Dyeing was conducted
using both ultrasonic power at 500 W and
conventional heating conditions. After selected time intervals,
0.5 ml of the dye bath was pipetted into test tubes and diluted
with water to 5 ml to measure its absorbance at 535 nm.