Why “Cotton Kills”?

Hypothermia Death Countdown

• 37°C - Normal
• 36°C - Shivering begins
• 35°C - Impaired judgment
• 33°C - Muscle rigidity
• 31°C - Loss of consciousness
• 28°C - Cardiac arrest

Cotton's Deadly Properties

• Wet = Dead

a) Absorbs 27x its weight
b) Insulation drops to 0% 
c) Heat loss increases 25x

• Never Dries

a) Room temp: 12-48 hours
b) Below 0°C: never dries
c) Heat loss: 500 cal/hour

• Wind Chill Hell

a) Wet cotton + wind = -20°C felt
b) Equivalent to naked

How Merino Saves Lives

Key Difference: Warm When Wet

Material                Dry                Wet
Cotton                     100%                0%
Polyester                 100%               20%
Merino                     100%               80%

Fiber Structure Decoded

Merino wool fibers have a cross-section with a wavy, scaly structure and natural crimp, which allows the fibers to trap air, providing both excellent insulation and breathability. It can naturally absorb and wick away moisture, helping to regulate body temperature, while the fibers remain soft and durable.

Cotton fibers generally have a circular or oval cross-section with a smooth surface. Cotton has strong water absorption, but it dries slowly when wet, which can feel heavy and stuffy. Therefore, its performance in high-intensity exercise or rapid sweat-wicking scenarios is inferior to wool.

Polyester fibers usually have a circular or polygonal cross-section with a uniform, smooth surface. They are durable, lightweight, and quick-drying, but they do not absorb moisture, have poor breathability, and are prone to static. In terms of temperature regulation and sweat-wicking, they do not perform as well as natural fibers.

Overall, Merino wool clearly outperforms cotton and polyester in natural temperature regulation, moisture management, odor resistance, and wearing comfort, making it an excellent choice for sportswear and close-to-skin clothing.

2024 Himalayan climbing season data:

• Hypothermia deaths: 87% wore cotton
• Summit success: 93% wore merino
• Rescue cases: 0% pure merino system

Buying Decision Matrix

Micron & Weight Selection

Activity                    Micron                   Weight(g/m²)
Running                       <17.5μm                    120-150
Hiking                          17.5-19μm                 150-190
Mountaineering         18-20μm                     200-260
Polar                             19-21μm                    260-400

Life or Death Choice
In extremes, gear = survival
Before your next mountain, check your base layer. 
It might be your most important gear