Where does wool come from?
All of the sheep's fleece is not wool. Sheep have two types of fiber in their fleece. One is long, coarse guard hairs that form an outer protective layer over the second, an undercoat made up of softer, finer, downy fibers. It is this soft undercoat that we call wool. One of the goals of eleven millennia of sheep breeding has been to completely eliminate the guard hairs from the sheep's coat. Merino wool, the finest, softest wool around, should have no trace of guard hairs, while some mountain breeds still have quite a lot of hair.
Kemp is another ingredient of some wools that many consumers consider undesirable. Kemp is a short, hairy, very coarse fiber that is usually chalky white, opaque and very brittle. Harris Tweed fabrics have visible quantities of kemp. Kemp accepts dye only very reluctantly, so it stands out clearly against a dyed background. The carpet yarn industry actually adds kemp to some of its yarns to give them a distinctive texture and appearance.
What makes "good" carpet wool?
Wool is sorted by its characteristics: fiber length, fiber diameter, color, cleanliness, how it was removed from the sheep's skin, and region or country of origin. The words fine and coarse refer to the size or diameter of the fiber; they are not a judgment of quality. There are several count systems used to denote fiber size. One, derived from the English worsted yarn system, is a scale that runs from the 30's to an abstract ideal of 100. The higher the count, the finer the fiber. Merino, the finest wool breed, is 60's - 100, crossbreeds are 36's - 60's, and carpet wools fall at 46's and under. The micron count system is more direct. The count number represents the actual size of the fiber in microns, so the higher the number, the coarser the fiber. This is the system that is used most often now.
As far as color in wool is concerned, whiter is better; at least, it is a factor in the price, with super white wools costing more than yellowish wools. In fact, though, very white is most important only if you need to dye the fiber bright, clear colors.
Crimp refers to the waves you see in a lock of wool. Crimp gives wool its amazing springiness and elasticity, and is one of the reasons that wool is the easiest fiber of all to spin. On the whole, finer wools have more crimp than coarser ones. A good carpet yarn will have some crimpy fibers in it so the carpet will resist crushing and creasing from the weight of furniture. Lamb's wool is finer than that from the same sheep as an adult. Virgin wool is fiber that has not been spun before.
How is wool produced?
Wool right off the sheep is called grease wool until it has been scoured, or washed, to remove the oils, dry sweat and dirt from the fibers. Even wool that appears clean can lose as much as 50% - 60% of its weight in scouring; however, it will lose very little of its VM (vegetable matter). To get rid of the VM, especially burrs, wool must be carbonized. This process involves soaking the wool in dilute sulfuric acid and heating it to a high temperature. The VM turns to ash and will fall out in the carding process. Carbonizing is very hard on wool fiber; it can make the wool brittle, yellow, weak and lusterless. To make a strong, durable carpet yarn, it's best to use wool with little or no VM or to learn to live with a few leaves in your yarn.
Spinning wool into yarn involves drafting or pulling the fibers out, and twisting. Twist is what gives strength and integrity to the yarn. Longer fibers need less twist to be strong, and the heavier the yarn is, the less twist it needs. Softer twist yarns, like you would find in sweaters and blankets, are lofty and warm, but they will pill and will not stand up to much abrasion. Carpet yarn should have some resilience so it will bounce back from the pressure of furniture, but it should be made of longer staple fibers and have enough twist to resist abrasion and pilling.
Is it a good fiber for floors?
Yes, for many reasons. Wool is a protein fiber, not cellulose like most plant materials. Its outer layer is a thin water-repellent coating that resists the absorption of water. This is why a wool carpet allows liquid spills to bead up on its surface for a time. Woolen yarns also trap air, making wool carpets great insulators of heat and sound. Another important characteristic of wool is that it is highly fire resistant. Unlike the plant fibers, wool may smolder but its flames are self-extinguishing. In fact, constant moisture can do more damage to wool than fire.
How should I care for Wool Carpets and Rugs?
Wool carpets and rugs are not immune to mildews and molds, so wool carpeting should be used in dry, well-ventilated places and should not be allowed to stay damp if they do get wet.
Wool carpet is sensitive to some chemicals, especially alkalis. Never, ever use chlorine bleach on wool rugs; however, hydrogen peroxide can be used if applied sparingly and carefully. When cleaning spots and stains on wool carpet, use a neutral detergent like dishwashing liquid rather than laundry detergent or household cleansers. Avoid soap and soda, but diluted ammonia, a mild alkali, is safe. Because wool carpets tolerates acid solutions quite well, a little white vinegar added to the cleaning liquid can also be used to cut grease and oils. Very hot water can encourage dyes to bleed. Lukewarm tap water (100 F) is safest, but hotter water can be used sparingly for stubborn greasy spots. Wool carpeting also tolerates dry cleaning solvents well.
Several types of moth and beetle grubs also find wool carpet protein very appealing. Prevent their damage with regular vacuuming, giving special attention to areas that are rarely disturbed. Carpeting under furniture should be cleaned regularly and rugs should be turned a couple of times a year to evenly distribute wear and exposure to sun. Thorough vacuuming also extends the life of the wool carpet by removing the dirt and sand particles that can act like sand paper, rubbing against the yarns and weakening them.
The presence of wool in a carpet signifies quality, durability, safety, comfort, beauty and luxury. Wool is the classic carpet material, being tough yet flexible and resilient, soft underfoot, and easy to dye any color imaginable.