Desizing Chemistry
Protective coatings applied to warp yarns must be completely broken down and removed before the fabric can be dyed or finished. Chemical processes involved in warp sizing degradation break the long-chain starches or synthetic polyvinyl alcohols into smaller, water-soluble molecules during the desizing stage. This hydrolysis reaction requires specific enzymes or oxidizing agents to ensure complete breakdown of the film.
The reaction terminates when all sizing agents are dissolved, leaving the yarn soft and receptive to dyes.
Mechanical Degradation
High mechanical stress during the weaving process can also cause pre-emptive cracking of the size film on the yarn surface. This physical breakdown results in increased friction in the loom and leads to excessive yarn breakage and shedding of size powder. This shedding generates high amounts of dust in the weaving shed.
Monitoring loom tension prevents this issue.
Temperature Influence
Thermal control in the wash boxes is critical for ensuring that the degraded size molecules do not re-deposit onto the fabric. High temperatures keep the dissolved polymers in a soluble state, allowing them to be rinsed away easily. If the wash water temperature drops, the size re-solidifies.
Finishing Success
Incomplete degradation of the size film creates a barrier that prevents subsequent dyes from penetrating the yarn core. This failure causes uneven dyeing, blotchy surfaces and poor color fastness in the finished fabric. Ensuring complete removal of these compounds is the most important step in preparing fabric for the dyehouse.
