Greige Fabric Storage Requirements and Preservation Standards
Unfinished greige fabric preservation demands humidity control between 50 and 65 percent relative humidity to prevent size retrogradation and oil oxidation.
Starch Retrogradation
Molecular Realignment
Adhesive sizing formulations for warp yarns rely on starch polymers that undergo structural changes during cooling and storage. This crystallization process is starch retrogradation, where amylase and amylopectin chains realign and form insoluble, rigid structures. It occurs as the cooked starch gel cools, causing the polymer chains to associate via hydrogen bonding and squeeze out trapped water.
This transition from a flexible gel to a crystalline state reduces the flexibility of the size coating on the yarn, making the warp sheet brittle during subsequent high-speed winding and weaving operations.
Viscosity Alteration
As retrogradation progresses, the viscosity of the sizing paste increases and can become highly irregular. This increased viscosity leads to uneven application on the warp yarns, resulting in some strands being over-sized and others remaining under-protected. Over-sized yarns become brittle and are prone to cracking, while under-sized yarns lack the abrasion resistance needed to survive the looms.
Controlling the aging of the size mix is therefore vital for uniform coating.
Weaving Performance
Hardened sizing films that have undergone this recrystallization fail to flex with the yarn during the high-tension environment of modern weaving. When starch retrogradation occurs, the size coat flakes off the yarn during reed and heald movements, creating excessive dust in the weaving shed. This flaking weakens the warp threads, leading to frequent breakages and reduced loom efficiency.
Preventing this flaking ensures smooth mechanical operation.
Thermal Prevention
Sizing departments prevent this crystallization by keeping the starch paste heated above its gelatinization temperature during application. Adding synthetic binders or chemical retrogradation inhibitors also stabilizes the formula against molecular realignment. Maintaining these warm, controlled conditions is crucial for consistent weave room performance.