Swimwear Fabric: Chlorine, Recovery and Colour Fastness

Chlorine Is What Kills Swimwear

Standard spandex degrades in chlorinated water. The elastane filament breaks down, the fabric loses recovery, and the garment goes slack at the seat and straps — usually after 20 to 40 pool sessions, not after years.

That is why pool programs and beach programs are not the same product. A beach or resort swimsuit sees salt water, sun and occasional rinsing. A training or team swimsuit sees chlorine several times a week, and needs either a chlorine-resistant elastane or a polyester construction that carries stretch through the knit structure rather than through a high spandex content.

Ask which one you are being quoted. The swatch will not tell you.

Recovery Matters More Than Stretch

For swim, recovery is the number that predicts complaints. A fabric that stretches 180% but returns to 98% of its original dimensions will outlast one that stretches 220% and returns to 92%.

Ask for recovery measured after immersion, not just dry. Wet elastane behaves differently, and a fabric that recovers well on a dry test bench can slacken noticeably in water.

Colour Fastness in Three Environments

Swim fabric faces chlorine, salt and UV at the same time — and they are separate fastness tests:

• Chlorinated water fastness — dyes bleach and migrate in pool water
• Sea water fastness — salt affects different dye classes differently
• Light fastness — sustained UV fades deep and fluorescent shades fastest

Deep navy, black and bright coral are the shades that most often come back as complaints. If your range leans on them, ask for fastness data on those specific colours rather than on a mid-tone standard.

Before You Commit

Request wet and dry recovery data, chlorine exposure results, and fastness ratings for your actual shades. Then wash-test a sewn sample — not a flat swatch — because seams and elastic bindings are where a swim garment usually fails first.