Wool & Sheepskin
Wool really is a special fibre. It is one of the oldest and most functional textile fibres known to man, having survived the test of time. On this page you will learn about:
- Wool: Its properties and the benefits of using it for medical conditions
- Combed Wool ( Footcare Lambswool), Pressure Smart XD and Wool Pile ( Nursing Fleece)
- Sheepskin production ( Australian Medical Sheepskin)
- Wool and Sheepskin Care with Woolskin
The CSIRO has produced a brochure which describes the Physical Structure and the Chemical nature of the Wool Fibre. To see this brochure, click: CSIRO
Wool surely is the "wonder fibre!" Today, there are many fibres, but as yet, science has been unable to produce another fibre having all of the properties of wool. Wool, for medical use, is either shorn from the sheep to produce Hospital Nursing Fleece, Lambswool products or left attached to the hide to create the Australian Medical Sheepskin.
Wool is special because :
- Wool is a natural insulator, trapping air within and between its fibres. Wool insulation is enhanced by the crimp or waviness of the wool fibre. Crimp ensures the fibres stand apart from each other, ensuring still air is trapped between them. This layer of trapped air is an excellent insulator- still air being one of the best insulators found in Nature. Wool used in footwear will keep feet warm when it is cold and near body temperature when it is hot. Trapped still air is most pronounced in sheepskin and wool-pile, making them excellent insulators against heat loss or heat gain. Sitting or lying on sheepskin or wool-pile insulates the user from the underlying surface. This means that the body is kept at an even temperature and the user feels more comfortable.
- Wool absorbs and wicks moisture, keeping your skin dry. In cold weather, even a little moisture on the skin will chill the skin; quickly reducing body temperature. In fact, the fibers can absorb up to 34% of their weight in moisture vapour without feeling wet; ten times as much as any synthetic fiber. The porous structure of the wool fibre also explains why wool is such a good thermal insulator, even without mentioning the mesh of the fibers, which creates millions of air pockets that further help to regulate temperature and humidity.
- Wool is resilient, spreading body pressure and reducing pressure points. Each fibre acts like a small spring. Wool is also a naturally strong fiber. It can bend back on itself 20,000 times without breaking. Compare this to cotton at 3,200 times, silk at 1,800, and rayon at only 75 times. Maximum pressure reduction has been found when the pile is clipped to 30mm, is homogeneous and of uniform length and density. Australian Medical Sheepskins have these properties together with a well defined staple and crimp. It is also has a straight to light curl appearance, is free of pilling, vegetable matter and felted wool.
These criteria must be met before a sheepskin can be classified as an Australian Medical Sheepskin (AS4480-1 1998). All of our HiTemp UR Medical Sheepskins exceed the above standard and are dyed a rich emerald green colour- for identification purposes; as prescribed by the Australia Standard.
The secret of wool lies in the structure of its fibres, which absorb moisture, insulate against heat and cold, resist flame, and maintain their resilience. Unlike cotton, linen, silk or polyester, wool fibres are composed of a central protein core that is covered with tiny scales, making them look like pine cones..see below.
Scanning electron micrograph of common fibres
Although the scaly surface tends to repel liquids, the fibre core is highly absorbent, taking in as much as 34% of its weight in moisture without feeling wet. Synthetics, in contrast, hold as little as 2%. By drawing moisture away from the skin, wool prevents clamminess in summer and helps to hold in heat during winter.
These overlapping scale edges all point in the same direction. Scales of adjacent fibres may interlock, causing felting and shrinkage. Such interlocking is irreversible. This means that wool that has shrunk or felted cannot be retrieved. When wool is washed, the scales act like a ratchet, causing fibres to move against one another. The scales also act as minute barbs, locking adjacent oppositely orientated fibres together. Fibre movement causes this locking action and the wool shrinks.
However, shrinkage and felting can be prevented by treating the wool with the Canadian Kroy process- also known as the Chlorine- Hercosett Process. Wool fibres are subjected to a mild treatment with chlorine and then a soft resin is applied. On heating, the resin forms a film over the scales and prevents fibre interlocking. Wool treated by the Chlorine- Hercosett process is also know as SuperWool.
Wool is fire resistant. Wool is naturally safe and does not have to be treated to become inflammable. While it can catch alight, it will not flare up nor support a flame. Once a flame is removed, a cold ash is left. This can be brushed away immediately. Wool does not melt when burned, and so cannot stick to the skin and cause serious burns. Because of these properties, wool fire blankets are effective in smothering a flame. Wool fibres contain about 15% moisture allowing them to resist flame without any additional chemical treatment. The wool will just char and self extinguish; giving off little heat.
Wool is non-allergenic.There is very litle scientific evidence that wool allergy exists. What is often perceived as an allergy is the prickling caused by coarse wool. Any suspected allergic reaction to wool may also be caused by dust mites in the wool. Research has shown that many people are in fact allergic to dust mite urine and faeces, rather than the mites themselves. Woolskin- the Lambskin Shampoo and Woolwash has been tested by WRONZ ( Wool Research Organization of New Zealand) and shown to kill and remove mites from wool and sheepskin. We recommend that all of our products be cleaned with Woolskin.
Wool wicks moisture: The porosity of the cells in the outer layers of wool fiber allows them to quickly and efficiently wick and evaporate moisture. Moisture wicked away from the skin keeps the skin dry and comfortable and helps to prevent skin breakdown in people susceptible to pressure sores.
Wool is a sustainable resource.
Combed Wool and Wool-Pile Production:
- Shearing:Sheep are sheared once per year, usually in the spring. Merino sheep need to be shorn at least once a year because their wool does notstop growing. If the coat is allowed to grow, it can cause heat stress, mobility issues, and blindness. After a sheep is shorn, a shed-hand picks the fleece up off the floor and throws it on to the wool classing table. Here, another shed-hand removes seeds and short or inferior pieces of wool from the edges of the fleece. The wool classer then classifies the fleece based on the wool properties of crimp, staple, fibre diameter and elasticity.
- Scouring: Select fleeces are washed to remove impurities, such as dirt, grease, grass seeds, burrs, and dried sweat. Impurities may account for 30 - 70 percent of the fleece weight. At this point, the wool is considered cleaned wool or scoured wool. The grease, mainly lanolin, that is removed is considered a valuable by-product. Lanolin, in its purified state, is used in creams, soaps, lotions, cosmetics and ointments.
- Carding: The wool is combed to straighten and untangle the fibers.
- Knitting: Carded wool in the form of a rope is used to produce Footcare Lambswool. Loose carded wool is also used to produce Wool-Pile; using the Sliverknit process. In this process, fibers are sent through a series of special carding machines that comb the fibers, aligning them parallel to one another. They are then gathered into a soft rope called roving or sliver - hence the term sliver knitting. The slivers are then fed into electronic knitting machines. The machines fine gauge needles, rotating in a circular motion, pick up fibers from each sliver in a predetermined sequence, locking them directly into a soft but strong polyester knit backing. Secured at one end, the fibers remain upright and perpendicular to the backing, allowing them to maintain their resilience, softness, breathability, comfort and light weight. After knitting, the wool-pile fabric is clipped to 30 mm for final use. SuperWool Underlays and Hospital Nursing Fleece products are produced this way.
Australian Medical Sheepskin Production:
About 1 in 20 sheepskins are good enough to be classified as an authentic Australian Medical Sheepkin. Those that do meet the standard are treated as follows:
Our raw sheep hides are obtained by the tannery from meat packing houses. Only those skins that meet the Australian Standard AS4480-1 1998 are selected for HiTemp UR tanning. The hides are selected for size and wool fibre properties. The leather must be free from excessive natural fat and grease, clean and free from faults such as large holes. Seed scar is permissible but seed is not.
The raw hides are washed several times to clean and prepare them for tanning.
The skins are tanned so that the wool and the leather are preserved. This makes them usable in Institutions and for personal home use. Chromium tanning ensures good durability of both the wool fiber and leather backing. The degree of tannage is measured by the shrink temperature. HiTemp sheepskins are tanned to the highest level and have a minimum shrinkage temperature of 110oC. This means that the skin will not shrink more than 5% when placed in water at this temperature for one hour. Glutaraldehyde is used in conjunction with the main tanning agents to add increased resistance to urine and perspiration.
Lambskins and sheepskins contain natural grease within their structure. The grease is removed by solvent degreasing; since it is has an offensive odour and would constitute a health hazard in a medical sheepskin. The solvents are removed from the skin during further processing. This is an important step in the tanning process and insures that a skin will remain soft and silky.
Next the skins are dyed a rich green emerald colour; according to the Australian Standard AS8840.1 1998. This dye is very colourfast. It may however, cause staining of bed clothing in certain cases of prolonged exposure to heavy perspiration. This should not be a problem when 100% cotton or cotton/polyester fabrics are used. Nylon should be avoided.
Lastly the skin side is buffed smooth and the wool side is trimmed, brushed and ironed to a silky finish using the latest technology.
Some of our HiTemp UR products are made from skins that have been perforated by an array of small holes. These assist air circulation through the sheepskin.
Washing Wool-Pile and Sheepskin:
Wool, whether it is combed, part of a sheepskin or knitted to form Wool-Pile; will shrink and felt if mistreated. The major causes of shrinkage and/or felting are agitation and high temperatures. Rubbing wool fibres against one another will cause felting. Placing untreated wool in the dryer will also cause shrinkage.
Careful washing and drying will maintain the hand or feel of wool and give articles an extended useful life. Click on washing instructions for the best way to wash sheepskin and wool-pile.
UseWoolskin- the Sheepskin Shampoo & Woolwash with conditioners. Woolskin contains: Tea Tree Oil; a natural anti-bacterial and anti-fungal that kills house dust mites- a major cause of house dust asthma.