What Is Textile Sizing Starch & Why Mills Use It
SEVAGRAM EXCIPIENTS
Before a single thread of fabric gets woven, the warp yarn it depends on has already been through a process most people never think about: sizing. Without it, the friction and tension of high-speed weaving would shred fragile yarn long before it became cloth. Textile sizing starch is what stands between raw yarn and a usable fabric.
What Is Textile Sizing?
Textile sizing is the process of applying a thin protective coating to warp yarn before it goes onto the loom. The size, typically a modified starch dissolved and applied as a film, penetrates and coats the yarn, binding loose fibers down and adding a temporary layer of strength and smoothness.
This matters because warp yarn on a weaving loom undergoes constant friction against the heddles, reed, and other yarn as it is repeatedly raised, lowered, and beaten during the weaving cycle. Unsized yarn, especially with weaker or hairier fibers, would break or fray under this stress long before a usable length of fabric was produced.
Why Modified Starch Is Used for Sizing
A good sizing starch needs to do several things at once: penetrate into the yarn structure rather than just coating the surface, dry into a flexible rather than brittle film, and then desize cleanly during later fabric finishing without leaving residue that affects dyeing or printing. Modified starches are typically used over plain native starch because they offer more controllable viscosity, better film flexibility, and more consistent penetration across different yarn types and counts.
What Affects Sizing Performance
- Yarn type and count – finer or weaker yarns generally need a higher size pickup to survive weaving.
- Loom speed – faster modern looms put more mechanical stress on yarn, increasing the importance of consistent, well-applied sizing.
- Desizing requirements – the starch film needs to be removable during later wet processing without leaving residues that interfere with dyeing.
- Weather and humidity – size film performance can be sensitive to ambient conditions in the weaving shed, which is part of why consistent starch quality batch to batch matters.
Frequently Asked Questions
Why does warp yarn need sizing before weaving?
Sizing protects yarn from the friction and tension of high-speed weaving, reducing breakage and fraying that would otherwise interrupt production.
Is sizing starch removed after weaving?
Yes. The starch film is removed during a later desizing step in fabric finishing, before dyeing or printing.
Why use modified starch instead of plain native starch for sizing?
Modified starch offers more controllable viscosity, better film flexibility, and more consistent penetration into the yarn compared to unmodified native starch.