Desizing Agents

Desizing agents remove the warp size — starch, polyvinyl alcohol (PVA), or carboxymethyl cellulose (CMC) — applied to yarn before weaving, so the fabric can absorb scour, bleach, and dye evenly. Two routes do the work: enzymatic desizing, where amylase hydrolyzes starch into soluble sugars, and oxidative desizing, where peroxide or persulfate degrades both natural and synthetic sizes. Choose the route by the size chemistry on the cloth, not by habit.

Amylase is specific. It cleaves starch at roughly 55-70°C within a narrow pH window, which is why a small acetic-acid addition is used to trim the bath to the enzyme's optimum. Because it targets only starch, it leaves the cotton fiber intact. Specify enzymatic desizing when the size is starch-based and fiber strength is the priority. The limit is real: amylase does nothing to PVA or acrylic sizes.

Oxidative desizing covers what enzymes miss. Sodium persulfate and hydrogen peroxide break down PVA and mixed-size systems, and an oxidative bath can combine size removal with bleaching in one step. The cost is selectivity: a strong oxidizer run too hot or too long can attack cellulose and lower fabric strength. For PVA or blended sizes, use the oxidative route and hold concentration, temperature, and dwell time to the size load.

• Enzymatic removal of starch size from cotton and cotton-blend greige goods before scouring
• Oxidative desizing of PVA, CMC, and mixed-size warp systems that amylase cannot break down
• Combined desize-bleach baths where oxidative chemistry removes size and whitens in one step
• pH conditioning of enzyme desize baths to hold amylase at its working optimum
• Pretreatment of woven fabric to improve wettability and dye uptake in downstream dyeing

• Amylase enzyme — PubChem
• Sodium persulfate — PubChem
• Hydrogen peroxide — PubChem
• Acetic acid — PubChem