Wool - a protein fiber
Wool is a generic term for the outer body covering of any quadruped. These coverings are primarily constructed of protein arranged in a linear fashion - hair. In general conversation wool means the outer covering of a sheep. But in a broader sense wool can mean part or all of the outer covering of a sheep, llama, alpaca, rabbit, dog, cat, cow, horse, goat, musk ox, or bison. You can find yarns from any of those animals except cats and dogs in any well-stocked yarn store. Each type of outer covering has different end uses, usually dependent on the fineness and length of the individual fiber. As a general rule, most of the animals listed above are raised only partly for their fiber, which is harvested each year by shearing. With the exception of the buffalo or bison which are being raised for meat, animals are not generally slaughtered for their fibers.
Wool is further divided into fleece and down. Fleece is usually the outer coat, but in breeds where the outer coat is quite coarse (horse, bison and cow), it can also be the term used for an inner coat. Fleece contains fibers from 2-8 inches in length and is of varying diameter, which can be measured on either the Bradford scale (mostly used for sheep’s wool) or in microns. Down is always an undercoat, and generally consists of fibers that are quite short – ¼ to ¾ inches in length – and fine, with diameter commonly measured in microns.
Fleece runs the gamut from rough and hard-wearing (think rugs and upholstery) to soft and fragile (think soft angora sweaters). Insulating properties are good.
Sheep’s wool is naturally flame-retardant. This makes it an excellent choice for items that will be worn in a camping environment, and anywhere you’ll be around a flame. Fine sheep’s wool is also a good choice for baby wear, since it’s a natural insulator, comfortable in all but the very warmest weather. Sheep’s wool has another interesting characteristic that makes it especially good for cold, wet weather. It will retain heat even when wet. This is what makes wool an especially good choice for socks, gloves and hats.
Down is normally the inner coat of an animal. Down is usually very warm and not particularly strong unless plied. Downs have a low resistance to abrasion and usually become quite fuzzy with wear. This characteristic can be enhanced or modified by blending down with other fibers.
Fleece and down can be cleaned in the same way. A 10-minute soak in hot soapy water followed by two or more rinses in water of the same temperature will clean these fibers nicely. You may want to add a splash of white vinegar to sheep’s wool fabrics to restore the pH to a more normal level. Wools should be laid flat or blocked to air-dry.
Bradford Scale for Sheep Wool - Types of Wool
Extrafine merino
Superfine merino
Fine merino
Standard merino
Medium wool
Coarse wool
Braid (very coarse) wool
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