Sizing is called heart of weaving. The materials which are used for sizing that is called size ingredients. A gelatinous film forming substance in solution or dispersion applied normally used for warp yarn but sometimes used for weft yarn before weaving is called size.
Size ingredients and their functions: Different types of sized ingredients are used for sizing. Followings are the main size ingredients used for sizing.
- Adhesive: Generally starch of maize, corn, rice, potato and CMC, PVC are used as adhesive. Tamarine is used as adhesive on jute yarn, the adhesive is in granule form that is mixed with water and heated to form a paste which ultimately becomes viscose fluid.
- To increase strength.
- To impart adhesion making the yarn less hairy.
- To increase abrasion resistance.
- To increase smoothness.
- To increase elasticity a stiffness.
- To reduce extensibility.
- Lubricants/Softener: Japan wax, Tallow, Mineral waxes, Vegetable waxes, Animal fats, Mineral oils and Vegetables are used as lubricants.
- It makes the yarn soft and slippery.
- It reduces stiffness.
- It increases yarn smoothness.
- It increases elasticity.
- Anti septic or anti mildew agent: Salicylic acid, Carbolic acid, Zinc chloride, Phenol is used as anti septic agent.
- It prevents mildew formation.
- To preserve size materials for a long time.
- It helps to store the yarn for a long time.
- To protect yarn from bacteria or fungus.
- Deliquescent or hydroscopic agent: Glycerin, Calcium chloride are used as deliquescent agent. Deliquescent agent is those substances which absorb moisture from air.
- It prevents excess drying of yarn.
- It helps to absorb moisture from air.
- To prevent the brittleness of size.
- Weighting agent: China clay, Sodium phosphate are used as weighting agent. These are used especially for those fabric or yarn that is to be solid or grey state.
- It increases the weight of yarn.
- To impart fullness and fell to the fabric.
- Anti foaming agent: Pyridine, Benzene are used as anti foaming agent.
Function: To prevent foam formation.
- Tinting agent: Blue is used as tinting agent.
Function: To increase lusture or brightness.
- Wetting agent: Sulphanol A, soap, avirol, magnesium chloride are used as wetting agent. The drawback of these substances is their high foaming ability and the foam is very stable.
- It increases size exhaust.
- To obtain a uniform distribution of sizing solution on yarn surface.
- It helps to wet yarn instantly.
So, when we will choose size ingredient for sizing we should remember the functions of size ingredients. Various dyes and chemicals manufacturing companies produce size ingredients, choose your favorite one from there.
Mercerizing is one of part of wet processing technology. Mercerizing is the special type of treatment. Mercerizing is done for get some special properties of the textile materials. By the mercerizing process the physical properties of the material changes. After scouring and bleaching process, mercerization is done.
Mercerizing is the process of subjecting a vegetable fiber to the action of a fairly concentrated solution of a strong base (Sodium hydroxide 50-70 deg Tw and 18 degree Celsius temperature) so as to produce great swelling with resultant changes in the fiber structure, dimensions, morphology and mechanical properties.
Mechanism of Mercerizing: We know that fiber cell structure is different from one to another. Some cell structure is triangular, some are oval, some are hexagonal, and some are zigzag and many more. When light falls on that cell it reflects the light as per its cell structure. Sometime this reflection is regular, some time it is not. It affects the luster of the fabric surface. For getting a regular reflection from the fiber it pass through a process called mercerizing process.
By mercerizing process the strength of the fiber increases up to 20-30%. Cotton fiber’s shape become round when it shrink in the solution of caustic soda (NaOH). The lumen becomes small and the cell wall become greater for this reason, strength of the fiber increased. The surface of the fabric become fine and light reflects on it constantly; so the luster of the fabric increase, the swelling power of the fiber also increase. Generally low twisted yarn is suitable for mercerizing. Mercerized fabric is more suitable for dyeing and printing than the bleached fabric.
Effects of mercerizing: Different types of changes are occurred for mercerizing in the cotton fabric. Following changes are the most important:
- Shrinkage in the area of the fabric.
- Tensile strength of the fabric increases.
- Fabric luster also increases.
- Hygroscopicity of the fabric increases.
- Capability for absorbing dyes increases.
- Preferential absorption of sodium hydroxide during the treatment.
- Mercerizing increased action of lower temperature.
- Possible compound formation soda cellulose.
Luster of the fabric is the most vital point. Attraction of the fabric depends on the luster of the fabric. Luster of fabric depends on various factors. They are as follows:
- Cross-section of the fiber.
- Staple length of the fiber.
- Wall thickness of the fiber.
- Concentration of Sodium hydroxide.
- Temperature of the mercerizing solution.
- Percent stretch.
- Yarn construction.
- Yarn twist.
- Doubling of yarn.
- Degree of singeing.
- Application of tension.
- Rate of drying.
Mercerizing increases the luster and strength of the fabric. Generally mercerizing is done for cotton. Mercerizing depends on the requirement of buyer. The price of the mercerized fabric is higher than bleached fabric.