| Tanning and Textiles-Mercerization |
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Mercerization is the treatment of cotton under tension with caustic soda solution at 15 – 25 °C for 25 – 40 s.
For this purpose fibres and fabrics are impregnated within a caustic soda solution. The concentrations normally used in practice for woven materials are in the range of 20 – 24 % NaOH (26 – 30° Bé), and for yarn, 24 – 26 % NaOH (30 – 32° Bé). Treatment with concentrated caustic soda destroys the spiral form of the cellulose, enhancing its ability to take up dyes. It also gives lustre to the fabric and a good dimensional stability for the woven fabrics, among other things.
For effective mercerisation, complete penetration (wetting) of the cotton fibres by the concentrated caustic solution is needed. Wetting agents are needed also to reduce the surface tension of the solution.
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