Beneficial properties of wool

12:03 Aistė Kesminaitė-Jankauskienė 0 Comments


I love wool -- it is warm in the winter an cool in the summer, it wicks away moisture and best of all -- it is natural! Of course this latter is only true if it is not dyed and not washed in sulphuric acid as it is mostly done in quite a few Australian, New Zealand and USA wool washing facilities. What gives wool it's wonderful properties?

Let's look at the wool fibre in more detail:




So much in such a small thing! Let's go over some of the characteristics.

FELTS NATURALLY The physical structure of the outer scaly layer of the wool fiber contributes to wool’s unique property of felting. Under the mechanical action of agitation, friction and pressure in the presence of heat and moisture, the scales on the edges of the wool fibers interlock, preventing the fiber from returning to its original position. Felting shrinkage is irreversible. Felting is also an advantage because it provides for a wide variety of non-woven felt fabrics and handmade felt articles. This is why wool is so strong and resilient when felted -- the thick mesh of wool fibers forms a strong and shape retaining mat, that will not tear, will not deform and can be reshaped if you make it wet.


DURABILITY AND RESILIENCE Each wool fiber is a molecular coilspring making the fiber remarkably elastic. Nature has folded the chemical polypeptide chains back upon themselves in such a way that they act like a coiled spring which elongates when it is extended and retracts when it is released. This molecular crimp, along with the 3-dimensional fiber, allows wool fibers to be stretched up to 50% when wet and 30% when dry, and still bounce back to their original shape when stress is released. But be careful: When wool is wet the fibers are weaker. Recovery from stress takes place faster when the fiber is in a humid environment; that’s why steaming a wool garment will freshen the fabric and why a steam iron is recommended for pressing wool. The flexibility of the wool fiber also makes it more durable. A wool fiber can be bent back on itself more than 20,000 times without breaking, compared to about 3,000 times for cotton and 2,000 times for silk. The natural elasticity of wool also makes woolen fabrics resistant to tearing. In addition, the outer skin of the wool fiber acts as a protective film, giving wool cloth improved resistance to abrasion.

RESISTANCE TO FLAME Because wool contains moisture in each fiber, it resists flame without chemical treatment. Instead of burning freely when touched by flame, wool chars and stops burning when it is removed from the source of fire. Wool is self-extinguishing. Wool does not melt when burned, and so cannot stick to the skin and cause serious burns. It will not support combustion; this is why wool blankets are recommended for use in extinguishing small fires. 


CHEMICAL STRUCTURE Wool is a natural protein fiber that grows from the follicles of the sheep’s skin. It is like human hair in that it is composed of keratin-type protein. Chemically these proteins contain 5 elements: carbon, hydrogen, oxygen, nitrogen and sulfur. These 5 elements are combined into 19 amino acids linked together in ladder-like polypeptide chains.

MOISTURE REGULATION/BACTERIA CONTROL Wool is a hygroscopic fiber; it takes up moisture in vapor form. Tiny pores in the epicuticle make the fiber semi-permeable, allowing vapor to pass through to the heart of the fiber. Wool can easily absorb up to 30% of its weight in moisture without feeling damp or clammy. The capacity to absorb makes wool a “temperature regulator” because it can protect the body in both cold and warm conditions. Wool always absorbs moisture from the atmosphere of greater humidity and releases it to the drier environment as it creates a balance in moisture conditions. Wool absorbs perspiration; thus it keeps a layer of dry air next to the skin which, in turn, helps to hold in body heat. Wool’s hollow fibre promotes air circulation and prevents bacterial growth. Bacteria can only grow in moisture; wool‘s natural fibre wicks moisture away from the skin preventing the conditions that allow bacteria to thrive. As wool absorbs atmospheric moisture, the hydrogen bond of water is broken and chemically reacts with molecules of the wool to generate heat. Wool garments are therefore regarded as good protection against hypothermia… a condition that occurs when sudden drastic lowering of body temperature causes the body to lose heat faster than it can be produced. The same principle of moisture contact on the skin acts to protect against hot weather as well. The body cools itself naturally with the evaporation of perspiration. Wool expedites this process by absorbing perspiration and keeping the same dry air next to the skin. This is why wool footwear is great for regulating temperature for your feet and making sure they do not sweat.




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