What Is Fabric Desizing?

Desizing refers to the process of removing the sizing material from a fabric. The warp yarns of fabrics such as cotton, viscose, and synthetic fibers are mostly sized before weaving. During the dyeing and finishing process, the slurry can affect the wettability of the fabric and hinder chemical contact with the fibers. Therefore, fabrics generally undergo desizing first.

Cotton fabric desizing has the function of removing some impurities from fibers. Synthetic fiber fabrics can sometimes undergo simultaneous desizing during the refining process. The methods for desizing various types of fabrics vary depending on the sizing material used, and there are four commonly used methods:

1. Enzyme desizing

Enzyme desizing belongs to biochemical desizing with a long history. The earliest natural fermentation method was used, and now amylase preparations are used. For fabrics with a majority of starch as the sizing material, they can be used.

2. Acid desizing

Only used for cotton fabric desizing and rarely used alone. Acid gradually hydrolyzes starch under appropriate conditions, transforming it into highly water-soluble products that are ultimately washed away by water.

3. Alkali desizing

This method is used for PVA based mixed slurries (including starch) and PA based slurries. All types of slurries will swell in hot alkaline solution, and the adhesion with fibers will become loose. PVA can be partially dissolved and can be washed away with hot water.

4. Oxidizer desizing

Oxidizing agent oxidize the slurry, degrade it until the molecular chains break, increase solubility, and remove it after washing, making it particularly suitable for PVA slurry.