Research Review: Is Merino Wool the Ideal Baselayer?

By Jackson Mann

BLUF

This study by Faisal Abedin (2023) developed and validated a novel methodology for evaluating the thermal and moisture buffering behavior of textiles under dynamic environmental and physiological conditions. Among the fibers tested, wool consistently exhibited stronger thermoregulatory performance—particularly in maintaining warmth during post-exercise recovery—compared to polyester, cotton, and viscose.

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Purpose of the Study

The research aimed to quantify the exothermic (heat-releasing) behavior of hygroscopic fibers such as wool during moisture sorption under transient conditions. A central objective was to propose and validate a new comfort metric—dynamic breathability—which accounts for the interplay of humidity, temperature, and body heat fluctuations over time.

Subjects

The study incorporated benchtop fabric testing, thermal manikin trials, and human subject experiments. Human trials involved 12 male participants wearing garments made of different fibers (wool, polyester, cotton, viscose) in a wind-controlled chamber (15°C, 50% RH, 1.7 m/s airspeed), simulating exercise and recovery cycles.

Methods

A multi-scale experimental approach was used:

• Fabric-Level Testing: Included ISO 16533 and a custom-built dynamic hot plate to assess thermal behavior during moisture absorption and desorption.
• Garment-Level Testing: Conducted with thermal and sweating manikins to simulate exercise-recovery transitions under both wind and no-wind conditions.
• Human Trials: Standardized movement and rest cycles were performed while collecting data on skin and clothing temperature, humidity, and subjective comfort.
• Isothermal Calorimetry: Measured the heat of wetting (sorption heat) released by different fiber types under controlled moisture uptake.

All procedures were conducted in climate-controlled laboratory environments, with additional calibration and correction techniques applied to improve manikin model fidelity.

Key Findings

• Exothermic Behavior: Wool exhibited the most pronounced heat release during humidity transitions, resulting in a warmer microclimate during the recovery phase.
• Thermal Buffering: Wool garments better retained warmth following activity, helping reduce post-exercise chill compared to the other materials.
• Moisture Dynamics: Polyester showed higher microclimate humidity and lower surface temperatures during recovery, which aligned with lower subjective comfort ratings.
• Dynamic Breathability Metric: A new measure of performance under transient conditions—dynamic breathability—was proposed and supported through testing.
• Manikin Data Adjustments: New correction methods improved the physiological relevance of thermal manikin results, though further refinement may be needed.
• Subjective Results: Participants consistently rated wool garments as more thermally comfortable during the drying phase, particularly in comparison to polyester.

Conclusion

This study advances understanding of textile performance under real-world, non-steady conditions. By integrating fabric, manikin, and human trials, the research introduces a replicable method for testing dynamic breathability and offers evidence that hygroscopic fibers like wool may provide more stable thermal comfort during changing activity and climate states. The findings are applicable to sportswear, outdoor gear, and potentially military apparel design, especially in environments where users experience rapid shifts in temperature and moisture exposure.

Sources

Abedin, F. (2023). Dynamic Breathability: Mapping the Gaps between Static and Dynamic Benefits of Fabric (Doctoral dissertation, North Carolina State University).