Post Mercerization fastness
Post Mercerisation Fastness Test:
Immerse the test sample and adjacent fabric for 5 minutes at 20C in a Caustic soda solution of 300 g/l concentration. Then rinse on the mercerizing frame by pouring over 1 litre water at 70C uniformly for 1 minute; then rinse the sample for 5 minutes in running tap water. Immerse the test sample without the frame in acetic acid solution (10ml/l glacial acetic acid), liquor ratio 50:1 for 5 minutes. Rinse with cold running water until neutralized and hang to dry in warm air at maximum 60C.
In mercerizing fastness test resistant specimen shows an apparent increase in depth of color. In such cases, only the changes in hue and brightness can be assessed using grey scale, without consideration of the increase in depth.