Pretreatment processes include desizing, scouring, and bleaching which make subsequent dyeing and softening processes easy. Uneven desizing, scouring, and bleaching in the pretreatment processes might cause drastic deterioration in the qualities of processsed products, such as uneven dyeing and decrease in fastness.
Objective of Pretreatment
* To Convert fabric from hydrophobic to hydrophilic state.
* To remove dust, dirt etc from the fabric.
* To achieve the degree of desire whiteness.
Steps in Pretreatment Process of Cotton and Natural Fibers:
Major steps involved in textile pretreatment are,
1.Singeing
2 Desizing,
3. Scouring,
4. Mercerization
5. Bleaching.
Steps in Pretreatments for Wool are:
1.Raw wool scouring; aqueous and/ or solvent washing
2.Carbonizing
3.Scouring (desizing)
4.Fulling /crabbing/thermo fixing
5.Easy-care treatments
6.Anti-felting anti-shrinking treatments
7.Wool Bleaching
Steps in Pretreatment of Silk
To prepare a silk yarn for dyeing and silk fabrics for dyeing and printing, it is necessary to partially or completely remove sericin, as well as natural oils and organic impurities. Depending on the percentage of sericin removed during scouring (sericin is present in raw silk in a ratio between 20 % to 25 %), the end-product is defined as unscoured (used only for shirts and suits), `souple' or degummed.
1.Degumming
2.Scouring
3.Bleaching
Pretreatment Of Synthetic Textile Materials
Although mots of the synthetics do not need to be given a very strong pretreatment however the possible steps in pretreatment of synthetics are
1.Desizing
2.Heat setting
3.Washing
4.Bleaching if necessary.
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