Merino wool is outstanding
When choosing high-performance apparel, the fiber composition determines everything — from comfort and odor control to durability and thermal regulation.
At first glance, a blend of fine Merino wool (16.5 microns) and synthetic fibers / Tencel® (Lyocell) may sound like a sustainable, natural alternative, but it comes with a price.
In practice, this combination sacrifices many of the technical and natural benefits that make Merino wool exceptional.
Below, we break down the key differences and explain why pure Merino wool — or a high mix of more than 85% Merino wool and less polyester hybrid — performs far better in every category.
1. Fiber Composition and Function
| Property | 100% Merino Wool (17.5 µm) | Merino / Tencel® | 86% Merino / 14% Polyester |
|---|---|---|---|
| Fiber Structure | Crimped, elastic, natural spring-like texture | Smooth, rigid cellulose fiber | Smooth but flexible and highly durable |
| Elasticity / Shape Retention | Excellent | Poor – Tencel fibers break under repeated bending | Very good – polyester stabilizes wool |
| Moisture Management | Absorbs up to 30% of weight without feeling wet | Absorbs quickly, dries slowly | Balanced – effective moisture wicking |
| Odor Resistance | Natural antibacterial (keratin + lanolin) | Minimal – cellulose encourages bacterial growth | Moderate – slightly reduced by polyester |
| Thermal Regulation | Active insulation – adapts to body temperature | Low density, flat fiber = poor insulation | Good – retains air and dries fast |
2. Durability – Martindale Abrasion Test
The Martindale test measures how many abrasion cycles a fabric can withstand before showing visible wear. Elasticity and fiber strength play a key role here.
| Material | Typical Martindale Value | Description |
|---|---|---|
| 100% Merino Wool (16.5 µm) | 20,000–25,000 cycles | Fine but resilient – performs well under normal use |
| 50% Merino / 50% Tencel® | 10,000–12,000 cycles | Significantly weaker – Tencel fibers break and pill easily |
| 86% Merino / 14% Polyester | 35,000–50,000 cycles | Very high durability – polyester reinforces the wool |
Conclusion: Tencel dramatically reduces abrasion resistance, especially in high-friction zones such as shoulders, elbows, and thighs. Polyester, on the other hand, strengthens the fabric without compromising comfort.
3. Odor Resistance and Hygiene
Merino wool naturally resists odor thanks to keratin proteins and lanolin that inhibit bacterial growth. Tencel, a cellulose-based fiber, holds onto moisture and provides a more favorable environment for bacteria.
| Material | Odor Control Rating | Notes |
|---|---|---|
| 100% Merino Wool | ★★★★★ | Can be worn for days without odor buildup |
| 50% Merino / 50% Tencel® | ★★☆☆☆ | Develops odor faster due to retained moisture |
| 86% Merino / 14% Polyester | ★★★★☆ | Slightly less resistant than pure Merino, but far better than Tencel blend |
4. Thermal Density and Temperature Regulation
Merino wool is an active fiber that traps air for insulation and breathes to regulate body temperature. Tencel’s flat, smooth surface lacks this structure, leading to reduced warmth and breathability.
| Material | Thermal Density | Thermal Performance |
|---|---|---|
| 100% Merino Wool | High – lofty and airy | Adapts naturally to temperature changes |
| 50% Merino / 50% Tencel® | Low – compact and moisture-prone | Feels cool but clammy during activity |
| 86% Merino / 14% Polyester | High – retains air and dries quickly | Warm, breathable, and stable comfort |
5. Overall Performance Summary
| Parameter | 100% Merino | 50% Merino / 50% Tencel® | 86% Merino / 14% Polyester |
|---|---|---|---|
| Durability (Martindale) | ★★★☆☆ | ★★☆☆☆ | ★★★★★ |
| Odor Resistance | ★★★★★ | ★★☆☆☆ | ★★★★☆ |
| Thermal Regulation | ★★★★★ | ★★☆☆☆ | ★★★★☆ |
| Elasticity / Comfort | ★★★★★ | ★★☆☆☆ | ★★★★☆ |
| Longevity & Value | Excellent | Poor – short lifespan | Outstanding – long-lasting performance |
Conclusion
While a Merino / Tencel / synthetic ® blend may feel soft and “natural” at first touch, it is a significantly weaker technical fabric in real-world use.
- Reduced durability and shape retention
- Poor odor resistance and faster bacterial growth
- Weaker temperature and moisture control
- Shorter lifespan and lower overall performance
More than 85% Merino wool provides unmatched comfort, breathability, and natural performance. A high mix Merino with a small amountpolyester blend offers the best of both worlds — keeping the feel of wool while adding strength, faster drying, and durability.