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.A generic term for compounds that are applied to warp yarn to bind the fiber together and stiffen the yarn to provide abrasion resistance during weaving. Starch, gelatin, oil, wax, and manufactured polymers such as polyvinyl alcohol, polystyrene, polyacrylic acid, and polyacetates are employed. 2. The process of applying sizing compounds. 3. The process of weighing sample lengths of yarn to determine the count. Now automation is used in sizing operation.
Objects of Sizing:
- To protect the yarn from abrasion
- To improve the breaking strength of the yarn
- To increase smoothness of yarn
- To increase yarn elasticity
- To decrease hairiness
- To decrease the generation of static electricity
- Pure sizing: when the size pick up % is about 3 – 10 % it is called pure sizing.
- Light sizing: when the size pick up % is about 11 -16% it is called light sizing.
- Medium sizing: when the size pick up % is about 17 – 40 % it is called medium sizing.
- Heavy sizing: when the size pick up % is above 40 % then it is called heavy sizing.
- Cost of land and machine is high
- Requires lot of labors
- Requires utility like gas, electricity etc and their cost is high
- Cost of ingredients
- The process is long and it takes time
- There is a risk of degradation of yarn
- The yarn diameter is increased
- Requires robust loom
- It increases yarn stiffness
- The fabric needs to be desized before use
- Need knowledge and information about the size ingredients
- There is a risk of pollution
- Sizing changes the shade of colored yarn
- 100% size material cannot be removed
- Size material presence leads to uneven dying