Category: Shrinking

Fiber Mechanics: Relaxation vs. Thermal Consolidation

Garment shrinkage is governed by mechanical tension release. During high-speed industrial knitting, cotton yarns are pulled under intense mechanical stress. When subjected to warm water and mechanical tumble agitation, the yarn relaxes to its natural coiled state (relaxation shrinkage). If high dry heat (>65°C) is introduced, microscopic hydrogen bonds between cellulose chains permanently reform in a compacted configuration. Understanding fiber blends is critical: pure cotton shrinks predictably by 5% to 10%, while synthetic polyester requires heat above its glass transition temperature (~70°C) to alter dimensionally.