Mother nature did a remarkable job designing a wool fiber.
Rather than ignore moisture like a synthetic fiber, wool
uses moisture to keep you comfortable. Each wool fiber consists of an absorbent
(hydrophilic) core surrounded by a nonabsorbent (hydrophobic) shell.
The moisture that comes off your skin is full of latent heat, and if you
ventilate all the moisture away, the heat goes wit it; hence the constant layering shuffle
with synthetic fabrics.
But with wool, the heat stays with you because the shell of the fiber separates the
moisture and the air to avoid evaporation chill.
That's why wool keeps you warm even if you get wet. Wool works in open air like a
wet suit works under water with one added feature: wool also uses stored moisture to
cool you down when you heat up. The result is an amazing flywheel effect that adjusts
naturally to keep you comfortable over a wide range of conditions.
Body Moisture transformed into vapor contains significant latent heat which wool can absorb. The
vapor moves through the hydrophobic sheath of each wool fiber into the fiber's core. This keeps heat
in the clothing envelope around the wearer withou evaporation heat loss.
Insulating systems that wick away all bio-vapor also remove the latent heat
it contains. To compensate, they need additional insulating loft and more on-and-off
layering adjustments to match ventilation to activity level.
Dew Point Control
Low body heat output in extreme cold will often locate the dew point (point of 100%
relative humidity) to the exterior region of the insulation layer and inside the exterior
shell garment. Since Omnitherm absorbs body vapor and uses its latent heat, it doe
not lose insulation ability when the dew point moves inside exterior shell layers with
breathable membranes in extreme cold conditions. This is especially important in
stationary or very low activity operations.
Insulating fabrics that ventilate all vapor are less effective when condensation of vapor
occurs inside exterior shells. Moisture left in the insulation greatly increases the
amount of insulating loft or bulk required to provide the equivalent insulation.
Unlike synthetic fibers, wool fibers have the ability to conduct and hold heat. This
"sensible heat" is stored in the wearer's insulating envelope. This provides a
flywheel effect -- self-adjusting to reduce the amount of fiddling with the layers as
weather and activity levels change. Wool can also absorb radiant heat from the sun
or from a fire without danger from flammability.
Insulating Coefficient (clo)
Insulating effectiveness in all clothing systems is provided by dry, trapped air.
The removal of body moisture into the wool fiber core keeps the trapped air in Omnitherm
drier, greatly increasing the insulating coefficient of the fabric.
Even when soaked, Omnitherm maintains sufficient insulating ability to help avoid