Lycra Fabric Questions, Answered: Women's Pants, Dive Skins, Webbing, Duvets & Cashmere Yarn

Every year I review 200+ fabric samples and finished garments before they get the OK for production. In 2024, I rejected 11% of first deliveries—most often because "stretch" meant something different to the mill than it did to our spec. Lycra is one of those words that gets thrown around like it just means "tight." It doesn't. Lycra is a branded elastane fiber, and whether it works in a product depends on the blend, the construction, and the test method.

Here are the questions I get most often from fabric and product buyers, plus a few you didn't know to ask.

What is Lycra fabric?

Lycra is a brand of elastane—often called spandex in North America. When a tag says "Lycra," it means the elastane fiber in that fabric was made to The Lycra Company's quality standards, not just "any stretchy thing." Lycra is almost always blended with another fiber: cotton, nylon, polyester, wool, even cashmere. The elastane content is typically 2% to 20% of the total blend.

In my quality specs, the percentage is never optional. If I see "Lycra" without a percentage, I treat the spec as incomplete. For a stretch garment, I use ASTM D2731 for elastic yarns and AATCC 135 for shrinkage in home laundering. Those tests won't tell you everything, but they tell you more than a hangtag.

Women Lycra pants: why do some keep their shape and others don't?

The common assumption is that more Lycra equals better recovery. That's not what I found in practice. A 7% Lycra knit can bag out while a 5% Lycra knit with a tighter loop structure stays put. The percentage is only half the equation. The other half is how the fabric is knitted or woven, and how the seams are finished.

When I qualify a run of women Lycra pants, I ask for two numbers:

• Elongation after repeated stretch, tested per a standard method like ASTM D2731 for elastic yarns.
• Recovery after load removal after 30 minutes—also called "growth." I prefer less than 1.5% growth for a fitted legging.

I also run a home-laundry shrinkage test before cutting. A 10% shrink in the first wash is a self-inflicted customer complaint.

Henderson Lycra dive skin: is it worth the brand premium?

Henderson uses Lycra fiber in many dive skins and wetsuit linings. What you're paying for is not the brand logo; it's the specified thickness, chlorine resistance, and UV protection. I've tested unbranded dive skins that claimed "lycra" but had a lower elastane content and a looser knit. After a season, they bagged at the elbows and knees. The Henderson version held up much better in a stretch-and-recovery test.

This is also where my "time certainty" mindset kicks in. If you need a dive skin for a specific trip, don't gamble on a vague "it'll ship in time." Last year I ordered an unbranded one with standard shipping, and it arrived two days after the boat left. Looking back, I should have paid the extra shipping fee and bought from a dealer that had stock. The rush fee was small compared with the cost of missing the trip.

How should I wash Lycra garments to make them last?

Washing is where most stretch garments die. Hot water, fabric softener, and dryer heat break down elastane over time. I've seen an expensive pair of women Lycra pants lose their recovery in 10 washes because fabric softener was used every cycle. Lycra fiber itself is durable, but chlorine, bleach, and high heat attack it.

On our care labels, we recommend cold wash, mild detergent, and no dryer if possible. If you must use the dryer, use low heat and remove the garment while slightly damp. For swimwear and dive skins, rinse in fresh water after exposure to salt or pool chlorine. A Henderson Lycra dive skin will last far longer if you never leave it wadded up in a dive bag.

Does heavy webbing need Lycra?

Not the kind of heavy webbing you're thinking of. "Heavy webbing" usually means nylon or polyester strapping with low stretch—backpack straps, dog leashes, tie-downs. Adding Lycra makes a strap elastic, which is good for waistbands and garters, but bad for load-bearing gear. Stretch in a tie-down means the load shifts.

In quality terms, I'd ask for breaking strength and elongation at break. If a supplier says "elastane webbing" and you're using it for a lifting strap, don't. For flat elastic trim, Lycra can provide consistent stretch recovery that cotton or rubber elastic can't match. But for heavy webbing, low stretch is usually the feature.

Studio McGee duvet cover: should a duvet cover have Lycra?

A duvet cover doesn't need Lycra to be good. But in the home textile category, many duvet covers that promise a smooth, wrinkle-resistant fit are made from cotton sateen with a small percentage of elastane. If you're looking at a Studio McGee duvet cover or a similar one, check the fiber breakdown rather than assuming the brand name tells you everything. In my inspections, a cotton-lycra sateen with 3-4% elastane survives repeated laundering better than a 100% cotton cover with no stretch, because the fiber creeps less at the seams.

That said, this is a context-dependent call. If you sleep hot, pure cotton percale may feel cooler than a stretchy sateen. The polyester in some sateen weaves can trap heat, independent of Lycra. So don't buy a duvet cover just because it says Lycra; check the full fiber list.

What makes the best cashmere yarn?

For knitwear, the best cashmere yarn is the one that won't droop after three wears. A 100% cashmere yarn is soft and breathable, but it can stretch at the cuffs, collar, and hem. That's why many premium knitwear mills add 2-5% Lycra or elastane to cashmere yarn. The elastane is usually fed as a core or wrapped around the cashmere, so you keep most of the hand feel while getting shape memory.

When I evaluate cashmere yarn, I ask for the composition percentage and a pilling test. Cashmere is a delicate fiber, and a well-blended yarn with Lycra will often outperform pure cashmere in a fitted sweater. For a drapey scarf, pure cashmere is fine—the stretch isn't necessary. But for fitted garments, a little Lycra is a feature, not a compromise.

One question almost nobody asks: what test method is in the spec?

When a new mill sends me a Lycra fabric, I ask how they test stretch and recovery. It's a boring question, but I ask it in every vendor audit. You'd be surprised how often the answer is "we use the hand-feel method." That is not a test method.

Honestly, I'm not sure why some mills still refuse to publish recovery data. My best guess is they don't want to be held to it. But if a vendor can show me a reliable test report, I'm much more likely to approve their fabric. If they can't, I treat the "Lycra" label as decoration until proven otherwise. (Note to self: always ask for the test report, not just the hangtag.)

If you're buying anything with Lycra—whether it's women Lycra pants, a dive skin, a duvet cover, or cashmere yarn—the smartest question you can ask is: "What exactly is in here, and what test proves it will hold up?" A good supplier will be happy to answer. A vague one will not.