The Science Behind “Warm and Dry” and Why Llama Fiber Does It Better. Part II
Llama fiber’s ability to maintain a constant level of water vapor accounts for its dependable protection in weather extremes.
To understand the reasons for llama fiber’s superior protection, these topics are addressed in this series of discussions:
- Properties of water vapor that allow it to both cool and heat the body.
- How llama fiber uses water vapor to maintain dependable comfort.
- How llama fiber creates a personal atmosphere for the individual.
Part 2: Llama Fiber and Water Vapor: Unmatched Insulating/Wicking in the Same Fiber
Llama fiber’s ability to maintain a constant water vapor content, allows it to provide a constant temperature and moisture level within the personal atmosphere of their fleece, providing dependable protection in all conditions.
Llama fiber is hygroscopic. It can attract water vapor molecules from the surrounding atmosphere and hold them on the surface of the fiber as dispersed, individual molecules. Llama fiber holds these molecules by adsorption, a process that utilizes passive, non-molecular bonds that are easily broken. Adsorption differs from absorption, a process which bonds groups of water molecules (liquid) by active molecular bonds to the absorbing fiber, requiring heat to be broken and dispersed.
A fiber’s hygroscopic properties or level of adsorption is expressed as “moisture regain” (MR). This value is determined by a laboratory test that weighs a sample of oven dried fiber, holding no adsorbed water molecules. After exposure to the atmosphere, it is reweighed. The difference in the dry and exposed weights is the result of hygroscopic moisture adsorption from the surrounding air. This weight difference, expressed as a percentage of the dry weight, is the (MR) moisture regain value.
This moisture regain value, can fluctuate a bit depending on air temperature and relative humidity, but the average value has a predictable range. The MR for llama fiber is +/- 27%, a high value in comparison to other fibers. Natural fibers, particularly animal fibers, tend to have higher MR values than plant fibers and significantly higher values than synthetic fibers. Atmospheric moisture content fluctuates, while the moisture carrying capacity of llama fiber is constant. In low humidity conditions it will retain moisture rather than give it up to the drier air. It will even pull water vapor from the drier air to hold its constant level of adsorbed moisture. In high humidity, the fiber will not hold more moisture, but will release excess moisture to the outside air.
When wearing llama fiber (llamas or people) and increased physical activity or air temperature cause perspiration, the liquid perspiration evaporates into water vapor, cooling the skin surface. The vapor migrates into the covering fiber which causes an increase in water molecules in turn raising the moisture content above the MR level. Water molecules then migrate to the surface of the fleece and dissipate into the atmosphere to reestablish the normal moisture content. Llama fiber is noted as having exceptional moisture wicking properties and its high MR is the reason.
MR also indicates the warmth or insulating capacity of a fiber. The clothing industry has traditionally attributed the insulating capacity of various textiles to the dead air space and loft they create. This is a factor, but it is minor by comparison. Llama fiber does enjoy an advantage in this measure of function because it is medullated or hollow.
The major reason llama fiber has greater warmth is its high MR value. It’s ability to hold a constant level of water vapor creates a heat reservoir by virtue of the latent heat of vaporization contained in the adsorbed water molecules. This allows conservation of a body’s generated heat as well as add solar heat contained in the surrounding atmosphere’s water vapor.
WICKING: WHY LLAMA FIBER DOES IT BETTER
Watch our video to see how llama fiber's extraordinary wicking ability is one of the many attributes that make it a superior material for use in outdoor protective clothing.
