TENCEL is a brand, not a single fiber. It covers two distinct fiber types: TENCEL Modal and TENCEL Lyocell. Modal is softer and drapes well. Lyocell is crisper, more breathable, and handles moisture more actively. Most underwear labeled 'TENCEL' uses one or a blend of both.
TENCEL is a brand, not a fiber type
Lenzing AG, an Austrian fiber company, owns the TENCEL trademark. Under that umbrella sit two separate fibers: TENCEL Modal and TENCEL Lyocell. Both come from sustainably sourced wood pulp processed in a closed-loop system that recaptures solvents. Beyond that shared origin, they behave quite differently on the body.
How Modal and Lyocell differ in practice
Modal starts from beechwood. The resulting fiber is fine, silky, and holds its shape after repeated washing. It drapes close to the skin and feels immediately soft, which is why it dominates premium underwear and loungewear.
Lyocell, most commonly sourced from eucalyptus, has a slightly crisper hand and a more active moisture response. It wicks and releases moisture faster than Modal, which makes it the better choice when breathability and a drier feel matter more than pure softness. [1]
| Property | TENCEL Modal | TENCEL Lyocell |
|---|---|---|
| Source | Beechwood | Eucalyptus |
| Hand feel | Silky, soft | Crisp, smooth |
| Moisture behavior | Absorbs well | Wicks and releases faster |
| Best for | All-day softness | Breathability, active use |
Why blending the two makes sense for underwear
A blend of Modal and Lyocell captures the softness of the first and the moisture management of the second. Compared to conventional synthetics or heavy cotton, TENCEL fibers generally produce a cooler, drier feel against the skin. [1] That matters most in areas where heat and moisture tend to build up.
Adding a stretch fiber is standard for underwear. Conventional spandex works, but bio-based alternatives now exist that deliver the same stretch with a cleaner production profile.
Oakman launches Fall 2026. Founding members get first access and founding pricing locked in. Reserve your spot.
Where Oakman fits
Oakman is built specifically for active men looking for scrotal cooling all day and want the option of a cold pack for cooling in the sauna or after heat exposure. The fabric is TENCEL MicroModal, naturally derived from wood pulp rather than plastic, blended with ROICA V550, a clean Japanese stretch fiber, rather than conventional spandex. The fit is athletic with a gusset, an extra panel that gives the testicles room and airflow. Dyes are bluesign approved, so what touches your skin is controlled all the way through the supply chain.
The whole point is a cooler, drier feel down where it matters, day to day and especially after heat exposure. If you use a sauna regularly, Oakman is made to work alongside that routine as the underwear you put on after.
Related reading
- Finnish Sauna vs. Infrared Sauna: What's the Real Difference?
- Sauna vs. Steam Room: Which Is Better for Your Health?
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Frequently asked questions
What is the difference between TENCEL Modal and TENCEL Lyocell?
Both are TENCEL branded fibers made from wood pulp, but Modal comes from beechwood and feels silky and soft, while Lyocell comes from eucalyptus and has a crisper feel with faster moisture release. For underwear, a blend of the two captures softness and breathability together.
Is TENCEL better than cotton for underwear?
TENCEL fibers generally wick and release moisture faster than cotton and feel lighter against the skin. Cotton is durable and familiar, but it holds moisture longer, which can feel warmer and heavier during activity or in hot conditions. [1]
Does scrotal temperature affect sperm quality?
Research shows that spermatogenesis is temperature-dependent and works best when the area sits a few degrees below core body temperature. [2] Studies have found that elevated scrotal temperature is associated with lower sperm concentration and reduced sperm quality. [3] This is established reproductive biology, not a claim tied to any specific product or garment.
Does underwear fabric affect genital temperature?
Fabric choice and fit both influence how much heat and moisture build up in the genital area. Naturally derived fibers like TENCEL tend to breathe better than synthetics, and looser fits allow more airflow than compression styles. [4]
What is bio-based elastane?
Bio-based elastane is a stretch fiber derived partly from plant-based feedstocks rather than entirely from petrochemicals. It delivers the same stretch and recovery as conventional spandex with a cleaner production profile.
This article is for general educational purposes and is not medical advice. If you have specific concerns about fertility or your health, talk to a qualified clinician.
References
- Comparative Assessment of Sensory Comfort Properties Across Eco-Friendly Textile Materials for Apparel. 2025. Journal of Natural Fibers (Taylor & Francis). [Link]
- Durairajanayagam D, Agarwal A, Ong C. (2015). Causes, effects and molecular mechanisms of testicular heat stress. Reproductive BioMedicine Online. [Link]
- Minguez-Alarcon L, et al.. (2018). Type of underwear worn and markers of testicular function among men attending a fertility center. Human Reproduction. [Link]
- Zleczewski, et al.. (2024). Garment fit, scrotal thermoregulation, and male fertility outcomes: a narrative review. Translational Andrology and Urology. [Link]
