Merino Short - 5"
Designed for everyday movement in merino.
Shop now100% Merino vs 95/5 Blends: Which Is Better for Activewear?
For decades, outdoor brands have sold 100% merino wool as the “purest” option. But when you look at performance, durability, and real-world wear — especially for activewear — a small blended percentage delivers dramatically better results.
This guide explains the science behind blends, why Estroni uses 95% merino + 5% elastane, and why pure merino isn’t always the superior choice.
1. The Problem With 100% Merino in Activewear
Pure merino is beautiful, soft, and naturally high-performance — but it has one major weakness:
It has no elastic recovery.
What this means in real life:
- The fabric stretches out and doesn’t spring back
- Fibres fatigue and weaken over time
- Stress points (shoulders, waist, thighs) develop micro-tears
- Pinhole damage is more common
- Garments lose shape after repeated movement
This is why hikers on Reddit often complain:
“My 100% merino shirt developed holes after a few months.”
Pure merino works great for:
- Socks
- Scarves
- Light sweaters
- Base layers with low abrasion
But for leggings, sports bras, tanks, and everyday active movement? It simply lacks structural reinforcement.
2. Why Add 5% Elastane?
At Estroni, we use 95% merino / 5% elastane — a tiny percentage that makes a huge difference.
Benefits of adding elastane:
- Better stretch for bending, running, and gym movement
- Better recovery so the garment returns to shape
- Less fibre breakage → fewer holes and longer lifespan
- Smoother surface → less pilling
- Better fit especially in leggings and sportswear
Even at only 5%, elastane dramatically improves structural integrity without reducing merino’s natural performance.
3. Does Elastane Reduce Odor Resistance?
No.
Odor control in wool comes from:
- Keratin protein structure
- Lanolin’s antimicrobial properties
- Wool’s ability to absorb moisture vapor internally
None of these rely on “100% purity”. They rely on how much wool interacts with your skin.
Estroni’s custom knit ensures maximum wool exposure and breathability — so odor resistance remains exceptional.
Read more: Why merino resists odor →
4. Durability: 95/5 vs 100% Merino
Real-world results make the difference easy to see:
| 100% Merino | 95/5 Merino-Elastane | |
|---|---|---|
| Stretch recovery | Weak | Strong |
| Resistance to pinholes | Poor | Excellent |
| Resistance to abrasion | Low | High |
| Longevity | 6–24 months | 2–5+ years |
| Shape retention | Weak | Consistent |
This is why nearly all modern high-performance merino brands use blends.
Learn more: Why merino gets holes →
5. Fit & Movement: Why Blends Are Superior
For leggings:
- 100% merino stretches out after 1–2 wears
- Seams bear high tension → risk of tearing
- No elasticity means poor sculpting
For sports bras:
- 100% merino cannot support high-movement compression
- Straps and bands lose shape quickly
For tank tops:
- Armhole and shoulder seams degrade faster
- Fabric droops with sweat weight
Estroni’s 95/5 blend fixes all of this.
6. Comfort Comparison
Comfort depends mostly on micron quality, not blend percentage.
Estroni uses:
17.5–18.5 micron Australian/NZ merino
- Ultra-soft
- Below the itch threshold (21 microns)
- Perfect for next-to-skin wear
7. Heat & Sweat Performance
Wool’s thermoregulation comes from the fibre, not the blend ratio.
95/5 performs the same as pure merino in heat:
- Cools when you sweat
- Warms when temperature drops
- Highly breathable
- UV protective
Blending does not reduce these benefits.
Read: Merino in Australian summer →
8. Why Estroni Uses 95/5 (Our Exact Reasoning)
After testing 100% merino, 90/10, 80/20, and several proprietary blends, the 95/5 balance delivered the best combination of:
- Durability
- Breathability
- Odor resistance
- Next-to-skin comfort
- Shape retention
- Movement performance
This blend also allows us to design true activewear — not just hiking base layers.
