What is Pretreatment? | Objective of Pretreatment | PretreatmentProcess of Cotton and Natural Fibers

Pretreatment:

Natural fibers and synthetic fibers contain primary impurities that are contained naturally, and secondary impurities that are added during spinning , knitting and weaving processes.Textile pretreatment is the series of cleaning operations.All impurities which causes adverse effect during dyeing and printing is removed in pretreatment process.

Pretreatment machine

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:

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