Should performance underwear use nylon or polyester?

Short answer: Both can work. Nylon (polyamide) blends usually feel smoother and softer with good abrasion resistance, while polyester blends are often more economical and dry quickly, with strong colourfastness when disperse-dyed. The better choice depends on hand feel, budget, colour needs and how the fabric performs in tests, not on the fibre name alone.

Typical differences

• Hand: nylon blends often feel silkier and cooler; polyester can feel slightly crisper.
• Abrasion: nylon is generally associated with good abrasion resistance, useful in high-friction zones.
• Moisture: both are low-absorbency synthetics; wicking depends heavily on yarn and knit construction or finishes.
• Odour: synthetics can retain odour more than cellulose fibres; finishes or blends may help.
• Colour: dyeing systems differ, which affects shade range and fastness.
• Cost: polyester is often less expensive, but quality fabrics of either can vary widely.

How to choose

• Define the end use: gym, running, all-day wear or cycling.
• Sample both fabrics in the same pattern and test moisture management with a method such as AATCC TM195.
• Test pilling and abrasion in friction zones.
• Wear-test and wash-test with the intended care instructions.

Limits

"Performance" is a marketing term. Avoid specific claims such as drying-time comparisons unless you have test data for your fabric. Recycled versions of both fibres exist; check feel and test results separately.

Where the fibre choice matters less than you think

In performance underwear, the yarn and knit often decide comfort more than the polymer. Microfilament yarns, channelled cross-sections, open knit structures and mesh panels can make either fibre feel cooler and move moisture better. Conversely, a dense, heavy knit in either fibre can feel warm. Comparing two fabrics only by "nylon" or "polyester" therefore misses most of what the customer feels; compare full specifications.

Dyeing and colour behaviour

Nylon is usually dyed with acid dyes and polyester with disperse dyes at high temperature. In practice this means the two fibres need different dyeing routes, and blends or panels combining both may need careful shade matching. Bright colours are achievable in both; deep shades on synthetics should still be checked for colourfastness to washing and rubbing, and dark polyester can show dye migration onto lighter trims if the process is not controlled.

A simple decision table

• Softest touch and smooth stretch: nylon/elastane is a common choice.
• Lowest cost and quickest drying: polyester/elastane is often preferred.
• Odour-prone sports use: test both after washing; polyester is frequently reported as holding odour more, but fabric and finish matter.
• Recycled content: both are available in recycled versions; verify with chain-of-custody documentation.

Facts, recommendations and uncertainty

Established: both fibres are low-absorbency synthetics with different hand and dyeing behaviour. Recommendation: test both in your style. Uncertain: which performs better for your customers until wear and lab tests compare them.

Sources and further reading

• AATCC TM195 — Liquid moisture management properties of textile fabrics
• ISO 12945-2:2020 — Pilling, fuzzing or matting, modified Martindale method
• ISO 6330:2021 — Domestic washing and drying procedures for textile testing

Standards and regulations are referenced by their published scope. Test parameters, cycles and pass levels should be agreed with your laboratory for the specific product; legal requirements should be confirmed for each destination market.