Size, its effects on yarn and its properties

Size is a gelatinous film forming substance in solution or dispersion form, applied normally to warp yarns. It can sometimes be applied to weft yarns.

Sizing is the process of applying the size material on yarn.

Objects of Sizing

1.     To protect the yarn from abrasion

2.     To improve the breaking strength of the yarn

3.     to increase smoothness of yarn

4.     To increase yarn elasticity

5.     To decrease hairiness

6.     To decrease the generation of static electricity

Technical changes that occur in yarn due to sizing

• Increase the abrasion resistance of yarn
• Increases the yarn breaking strength
• Increases the smoothness of yarn
• Makes the yarn stiff
• Increase yarn elasticity
• Decreases the hairiness of yarn
• Reduces static electricity formation
• Increases the diameter of yarn

The composition of size depends on the following factors

1. the type of fibre
2. the type of yarn
3. yarn quality
4. quality particulars of the fabric to be woven
5. machinery condition and the ambient condition of the loom shed
6. cost of size ingredients

Ingredients used in the size should have the following properties

• Ease of preparation
• Uniform viscosity
• Absence of prolonged congealing and kenning at application temperature
• pH control
• absence of foaming properties
• absence of prolonged tackiness
• compatibility with other components of the size
• stability towards decomposition
• ease of desizing