How to Wash Nylon
Nylon's amide bond yellows irreversibly in direct sunlight via UV photo-oxidation — no bleach reverses it. Chlorine bleach also cleaves the amide bond and weakens the fibre. Machine wash cold to 40°C, never use chlorine bleach, dry in shade. White nylon's biggest enemy is the sun, not the washing machine.
The Chemistry
Nylon is the generic name for a family of synthetic polyamide fibres. The two most commonly used in textiles are Nylon 6,6 (polyhexamethylene adipamide, produced from hexamethylenediamine and adipic acid) and Nylon 6 (polycaprolactam, produced by ring-opening polymerisation of caprolactam). Both are polyamides — their polymer backbones contain repeated amide linkages (-CO-NH-). This amide bond is the key structural feature of nylon and the source of both its useful properties and its specific vulnerabilities. The amide bond gives nylon fibre high tensile strength, excellent abrasion resistance, and good elasticity. It also makes nylon susceptible to two chemical attacks that are directly relevant to fabric care: ultraviolet radiation and oxidising bleaches. Nylon's UV yellowing is the most practically important of these. When nylon is exposed to ultraviolet light, the amide bond undergoes a photochemical reaction. The mechanism involves UV photons exciting electrons in the amide carbonyl group (-CO-), leading to formation of photo-oxidation products — including hydroperoxides, lactams, and various chromophores that absorb light in the yellow-to-orange visible range. The fabric visually yellows. This yellowing occurs most noticeably in white or light-coloured nylon and is initiated and accelerated by direct sunlight. It is irreversible — once the amide bond has been photo-oxidised and chromophore products have formed, no bleaching or washing can undo the chemical change. The chromophores have been incorporated into the polymer structure. Oxygen bleach (sodium percarbonate) and chlorine bleach can both oxidise some chromophore precursors and temporarily lighten slightly yellowed nylon, but once visible yellowing has occurred through sustained UV exposure, the change is permanent. This is why the standard advice for white nylon is to air dry in the shade, away from direct sunlight. Tumble drying is preferable to sun-drying for white nylon precisely because it eliminates UV exposure. This is the opposite of advice for most fabrics, where sunlight is beneficial for bleaching and deodorising. Chlorine bleach (sodium hypochlorite, NaClO) presents a separate chemical threat to nylon. The hypochlorite ion is a powerful oxidising agent that reacts with the amide bond directly, cleaving it and degrading the polymer chain. The result is fibre weakening and, at sufficient concentrations, fibre dissolution. Even dilute chlorine bleach (as in swimming pool water) causes cumulative degradation of nylon fabric with repeated exposure. Swimwear made of nylon or nylon-elastane blends deteriorates faster in chlorinated pool water than in salt water for this reason. Never use chlorine bleach on nylon, and rinse nylon swimwear thoroughly after swimming pool use. Oxygen bleach (sodium percarbonate, as in OxiClean) is safe for nylon and can be used at cold or warm temperatures for stain removal without risk to the fibre structure. Nylon is hydrophilic compared to polyester — it absorbs significantly more moisture (approximately 4% moisture regain vs 0.4% for polyester). This absorption is into the fibre itself, not just surface wetting. The absorbed water causes slight swelling and a modest reduction in tensile strength (approximately 15–20% wet strength loss — much less than viscose's 40–50%). The practical implication is that nylon dries more slowly than polyester but faster than cotton. Heat sensitivity: nylon 6,6 has a melting point of approximately 264°C and nylon 6 of approximately 220°C. Both soften significantly at lower temperatures. For ironing, the synthetic/low setting (approximately 110–120°C) is the maximum. Above this temperature, nylon fibres can develop a permanent glaze or sheen, and fine nylon fabrics (hosiery, mesh) can deform or develop holes. Do not iron nylon directly — use a pressing cloth. Static electricity accumulates on nylon in dry conditions because nylon has relatively low electrical conductivity. Anti-static sprays or adding a splash of white vinegar to the rinse water helps dissipate static charge. Fabric softener reduces static but leaves a coating on performance fabrics that can impair moisture-wicking properties.
Step-by-step
- 1
Machine wash cold to 40°C on a normal or gentle cycle — nylon is durable but heat-sensitive
Nylon is robust against mechanical washing — its high abrasion resistance means machine agitation does not damage the fibre. Cold to 30°C is best for swimwear and fine nylon fabrics like hosiery. 40°C is acceptable for performance wear and heavier nylon garments. Do not exceed 40°C — higher temperatures cause nylon to shrink slightly and can affect any DWR (durable water repellency) finish on technical garments.
- 2
Use oxygen bleach or standard detergent — never chlorine bleach on nylon
Chlorine bleach (sodium hypochlorite) directly attacks and cleaves nylon's amide bond, weakening and degrading the polymer chain. Even dilute chlorine bleach causes cumulative damage. Never use chlorine bleach on nylon. Oxygen bleach (sodium percarbonate, OxiClean, or similar) is safe for nylon and effective for stain removal. Standard laundry detergent is fine. Avoid fabric softener on performance nylon and swimwear — it coats the fibres and impairs moisture-wicking and quick-dry performance.
- 3
Rinse nylon swimwear immediately after chlorinated pool water — hypochlorite degrades nylon cumulatively
Chlorinated pool water contains dilute sodium hypochlorite at approximately 1–3 ppm free chlorine. Repeated exposure to even this low concentration degrades nylon amide bonds over time, accelerating wear of swimwear. Rinse nylon swimwear thoroughly with fresh cold water immediately after leaving a chlorinated pool. This removes the hypochlorite before it has extended contact time with the fabric. Salt water (ocean swimming) does not pose this specific chemical risk, though it should still be rinsed to prevent salt crystal abrasion during storage.
- 4
Dry in shade or tumble dry on low heat — direct sunlight irreversibly yellows white nylon
UV photo-oxidation of nylon's amide bond produces chromophores in the yellow-to-orange range. White and light-coloured nylon turns yellow from sustained sun exposure, and this yellowing is chemically irreversible — the polymer structure has changed. Dry nylon in the shade, indoors, or in an airy spot away from direct sunlight. Tumble drying on low heat is preferable to sun drying for white nylon precisely because it avoids UV exposure. For coloured nylon, UV also causes gradual colour fading through a different mechanism (dye photodegradation).
- 5
Iron on the lowest setting with a pressing cloth — direct contact at heat damages the fibre surface
Nylon softens at temperatures well below its official melting point. The synthetic or coolest iron setting (approximately 110–120°C) is the maximum. Never iron nylon without a pressing cloth between the iron and the fabric — direct contact causes surface glazing, sheen, or deformation of fine nylon fibres. Many nylon garments (hosiery, activewear mesh, technical fabrics) should not be ironed at all. For wrinkled nylon garments, hanging in a steamy bathroom is often sufficient.
- 6
Store away from light, especially fluorescent UV-emitting lights
Long-term UV exposure from storage near uncovered windows or under fluorescent UV-emitting lights (older fluorescent tubes emit UV at low levels) continues to yellow white nylon during storage. Store white nylon garments in a drawer, wardrobe, or opaque bag away from light sources. Black or dark nylon is less visually affected but the polymer still degrades. For long-term storage of white nylon, wrap in acid-free tissue paper to further exclude light and oxygen.
Nylon washing guide by type
| Type | Wash | Bleach | Drying | Iron | Notes |
|---|---|---|---|---|---|
| White nylon garment | Cold/30°C machine wash, normal cycle | OxiClean only — never chlorine bleach | Tumble dry low or shade dry — never direct sunlight | Lowest synthetic setting, pressing cloth, or skip | UV yellowing is irreversible — sunlight is the #1 threat |
| Nylon swimwear | Cold rinse after pool; cold hand or machine wash | None; OxiClean for stubborn stains only | Shade dry flat — no tumble dry for elastane blend | Never iron swimwear | Chlorinated pool water degrades nylon amide bonds cumulatively |
| Nylon activewear / sportswear | Cold/30°C machine wash, gentle cycle, inside-out | None; no fabric softener | Air dry or low tumble dry | Rarely needed; low if required | Skip fabric softener — impairs moisture-wicking properties |
| Nylon hosiery / tights | Cold hand wash or mesh bag gentle machine | Never | Dry flat or hang; no tumble dry | Never iron | Fine denier nylon tears easily in machine; use mesh laundry bag |
| Technical nylon outerwear (with DWR coating) | Cold/30°C gentle cycle, specialist technical wash | Never | Tumble dry low to reactivate DWR coating | Low, with pressing cloth | Tumble drying (not sun drying) helps restore DWR water repellency |
| Nylon-elastane blend | Cold/30°C gentle cycle, inside-out | Never — damages both nylon and elastane | Air dry flat; low tumble dry | Never iron if significant elastane content | Elastane degrades under high heat; chlorine bleach destroys both fibres |
Frequently asked questions
Why does white nylon turn yellow and can it be reversed?
White nylon yellows because UV light photo-oxidises the amide bonds in the polyamide polymer chain. The photochemical reaction produces chromophores — molecules that absorb light in the yellow-to-orange visible range — which become incorporated into the polymer structure. This is irreversible. Once nylon has yellowed from UV exposure, no bleach, washing, or treatment can undo the chemical change. Oxygen bleach (OxiClean) can slightly lighten early-stage yellowing by oxidising some chromophore precursors, but it cannot reverse advanced UV yellowing. The solution is prevention: always dry white nylon away from direct sunlight.
Can I use bleach on nylon?
Never chlorine bleach. Chlorine bleach (sodium hypochlorite) directly attacks nylon's amide bond, cleaving the polymer chain and weakening the fibre. Even dilute concentrations cause cumulative damage over time — this is why nylon swimwear deteriorates faster in chlorinated pool water than in salt water. Oxygen bleach (sodium percarbonate, in products like OxiClean) is safe for nylon and effective for stain removal. Always check the label if unsure whether a bleach is chlorine-based or oxygen-based.
Should I use fabric softener on nylon activewear?
No. Fabric softener deposits a waxy coating on fibres that reduces friction and static. On natural fibres (cotton, wool) this is generally harmless or beneficial. On performance nylon fabrics designed for moisture-wicking, the softener coating covers the fibre channels and gaps that enable moisture transport, significantly reducing the fabric's ability to wick sweat away from the skin. Performance activewear should be washed with standard detergent (or a specialist sportswear detergent) without fabric softener to preserve the technical properties.
How do I wash nylon hosiery without damaging it?
Fine denier nylon hosiery (tights, stockings, sheer socks) is vulnerable to snagging and tearing in machine washing — the drum agitates the fine fabric against other items, and zips, velcro, or sharp edges catch the delicate mesh structure. The safest method is cold hand washing with gentle detergent, no wringing, and drying flat or loosely hung. If machine washing, always use a mesh laundry bag to contain the hosiery and wash on a cold delicates cycle. Never put fine nylon hosiery in the tumble dryer — even low heat can cause fabric distortion or snag damage.