Fibre Structure and Crimp
A wool fibre is a complex structure. It is predominantly made of keratin, a protein that is present in our own skin and hair. Wool fabrics behave similarly to our skin and compliment the body in maintaining homeostasis in normal and extreme climatic conditions. The interlocking protein molecules within individual fibres gives its structure strength and resilience; it can be bent, flexed, and stretched in any direction 30,000 times or more without damage. Wool fibres have a natural curl called the "fibre crimp" which improves the elasticity of the fibre.
The fibre crimp is easily observed in raw wool. Furthermore, it promotes entrapment of air between the wool fibres which acts as an insulator against both hot and cold temperatures. The fibre crimp of the wool aids in the construction of technical performance fabrics that exhibit exceptional "condition buffering" abilities.
Every wool fibre is constructed from a unique series of proteins. A typical protein structure is illustrated here, however the nature of wool is so complex that science is yet to map its configuration entirely.
Wool’s Hygroscopic Ability
Wool is an active fibre that has hygroscopic characteristics allowing it to absorb and release moisture from the air. Fibres respond continuously to the moisture content of the surrounding air and will absorb or release moisture to maintain an equilibrium with their environment. The wool fibre is only able to absorb and release moisture when it is in a gaseous form, such as vapour. The hygroscopic ability of the fibres within woollen fabrics gives the fabric with the intrinsic ability to move moisture from one environment to another.
The movement of moisture through wool fabric applied to the body is governed by the difference in the moisture content of the microclimate, the area between the skin and the fibre, and that of the external surroundings. As the atmosphere will always contain some moisture unless artificially modified, so too will the wool fibre. Under normal atmospheric conditions the wool fibre will retain 14% to 18% of its own weight in moisture. However, the amount of moisture within the fibre at any one time is directly proportional to the relative humidity of the surrounding air. A wool fibre can absorb and release up to 35% of its own weight in moisture while staying dry to touch.
Moisture Vapour Absorbency
Wool has a natural ability to hold moisture vapour within and between the fibres whereas synthetics will only hold liquid either within OR between the fibres. A synthetic product that is designed to hold moisture within the fibre is acting in the same manner as a sponge and as such has no ability to release the liquid unless it is physically forced to do so.
The Heat of Sorption Response
When water molecules are absorbed by wool fibres they attach to specific sites within the protein structure. The resultant endothermic reaction causes a release of energy through heat (Fig. 5). Much of this energy comes from the effective condensation of the water vapour at these sites, but part results from the weak chemical bonding of water molecules to the material structure. Heat output continues until an equilibrium is reached between the moisture in the fibre and the external environment. When water vapour leaves the fibre it takes up energy again thereby removing heat. Consequently moisture absorption by fibres when the humidity rises causes the fibre temperature to rise, and moisture release following a decrease in humidity lowers the fibre temperature.
Heat Generation Through Saturation
Heat generated through the endothermic reaction is directly proportional to the dryness of the garment at the time of exposure to the moist environment.
The interlocking protein molecules within the individual wool fibres have the power to elongate, stretch and recover. The resilience of wool to degradation creates an extremely strong and robust fabric that will survive years of use and abuse.
Easy Care Instructions
Wool used has been "super-wash" treated, a process that modifies the outer surface of the wool fibre and allows neighbouring fibres to slide over one another. This prevents the interlocking or catching of the cuticles which causes the fibres to matt (or felt) together. This process does not affect any of the fibre performance features within the fabrics, it does make all garments made from Merino fabrics completely easy care.
Wools ability to retain moisture is also responsible for its static resistance. The retention of moisture within the fibre prevents a build-up of static electricity. This quality stops Merino fabrics from clinging uncomfortably and is especially important in safety areas where it is necessary to prevent sparking.
Pilling is the formation of small fibre balls on the surface of the fabric; the formation of balls is caused by fibres breaking and working themselves out of the fabrics. A badly pilled fabric will reduce durability, performance and decrease it’s aesthetic appearance. The same treatment that allows Merino fabrics to be machine washed and tumble dried also helps the fabric to resist pilling.
Given a similar fabric construction, wool will dry as fast as synthetic fabrics. Drying times of fabrics are controlled by the amount of liquid moisture held between the fibre matrix when the fabric starts its drying process, generally the thicker the fabric the more moisture it is able to retain and the longer it takes to dry. The surrounding atmosphere will then influence how long it takes for the moisture to be removed from the fabric matrix.
Dirt is kept from penetrating the surface of the wool fibre by the crimp and the scales. Its static resistance also helps to resist dust and lint from the air.
Wool is naturally flame retardant. A fabric made purely from wool is difficult to ignite, burns slowly, and has limited ability to sustain a flame. Burning wool fabrics are easily extinguished and the residue does not pose a severe burn hazard.
Merino fabrics provide protection when caught in a light shower of rain, or when exposed to water spray while boating or fishing. The wool fibre is primarily constructed of keratin, the same protein that makes up our skin. Wools natural spray protection is similar to our skins, it is able to repel water from its surface and transpire moisture vapour
Merino fabrics have a natural sun protection factor of UPF50+, which is equal to the leading sun protection clothing specifically designed for use in Australia.
Comfortable / Body Conforming
The diameter of the wool fibres used in the construction of a fabric will determine the degree of "itch" it will provoke. Broader fibres have less ability to bend or give which results in a prick when pressed against the skin. This pricking sensation creates the "itch" that some people may experience when wearing wool clothing. The characteristic "itch" factor of wool fabrics is overcome through selection of superior fine merino fibres which have the ability to bend or give when pressed against the skin. Due to the elastic nature of the wool fibre, Merino fabrics are able to conform to and follow the shape of the body. This enhances garment performance, wearer comfort, gives freedom of movement and assists the processes involved in micro-climate control by holding the fabric close to the skin.