How to Grade Pilling on Vintage Polyester Clothing: The Fiber-Snap Test

To grade pilling on vintage polyester clothing, separate two failures that look identical from three feet away: surface pilling (a Cosmetic Appearance defect) and fiber brittleness or breakdown (a Structural Integrity defect). Run a fiber-snap test on a hidden seam allowance — if the polyester filament bends without breaking, you're grading cosmetic pilling; if it snaps or crumbles, you're grading structural degradation, and that caps the garment at Fair or Poor regardless of how the surface looks.

We've graded polyester disco shirts, 90s track jackets, and double-knit leisure suits that looked identical in a flat lay photo and sold for wildly different prices because one buyer opened a not-as-described case over a shoulder seam that shredded on the first wear. The seller had called it Good based on pilling density. Pilling was never the problem. The fiber underneath it had already failed.

Why polyester pilling gets misgraded more than any other synthetic

Polyester is a thermoplastic fiber. Unlike cotton or wool, it doesn't degrade from moisture or moths — it degrades from heat cycling, UV exposure, and decades of friction that fuse and re-fuse the filament surface. That process produces two visually similar but mechanically different outcomes:

• Surface pilling: loose fiber ends tangle into small balls on the fabric face. The base weave underneath is intact. This is a Cosmetic Appearance issue and, on its own, rarely drops a grade below Very Good.
• Fiber breakdown: the filament itself has become brittle from age and heat exposure. The fabric looks thin, slightly shiny, or