The release of our latest shirt, the Blackwatch Woolen/Cotton Plaid, seems reason enough to delve into an informative rant on the specifics of wool. So here goes. What follows is a short overview of the intricate fiber that is wool.
The Wool pitch. Wool is a hard-wearing material, able to stretch 25-30% before breaking. Wool can be distorted many times and return to it’s original form, which makes it strong as well as wrinkle resistant. It is environmentally sustainable in that it's natural, biodegradable and renewable. The natural crimp of wool fibers make it a good insulator (contains between 2-12 crimps/cm). It's structure makes it breathable, both absorbing and releasing moisture quickly. Also drapes well, retains dye well and is odor resistant.
The Basics. Sheep’s Wool comes from the undercoat of its fleece. This is not to be confused with the outer covering of it's fleece called "sheep hair", which is made up of coarse, protective hair. The majority of all fine wool comes from Australia, New Zealand, China and the USA. Wool is a staple fiber, meaning many small staples (strands) of hair are twisted together to create a single yarn (similar to cotton). You can contrast a staple fiber with a continuous filament yarn (such as polyester). The quality of wool is determined by the fineness of the hair. These fibers roughly ranges from 10-45 microns in width. Anything 25 microns or finer is deemed suitable for next-to-skin apparel, while coarser widths are used for such things as outwear and carpet. In other words, if you got an old itchy woolen sweater, it should have been made from finer wool.
Worsted vs. Woolen. Woolen does not simply mean, "made of wool". It refers to a specific process. The two signature aspects of woolen fabric are; yarns spun with less twist and the use of shorter staple fibers. The lesser twist allows for the retention of wool's natural crimp which makes for a soft, lofty, insulated feel. The use of shorter fibers creates more small pockets of air, which provides insulation and breathability. Well suited to a variety of knit and woven applications. And of course, makes for a hell of a nice shirt.
Worsted yarns contain longer wool staples of 2 ½” or more. Worsted yarns are spun tightly to eliminate the natural crimp of wool. This fabric drapes well, is wrinkle and odor resistant and best suited to blazers and pants. Quality yarns, but sadly makes for an odd shirt.
Shearing. A sheep’s fleece is shorn once a year. Clippers are used to remove the wool, a process which takes only a few minutes. The fleece is then “skirted”, which simply means removing the unusable edges.
Scouring. Wool is not quite as clean as the Serta mattress sheep make it look. Approximately 50% of the weight of wool is impurities at this point. The fleece is gently propelled through a tank filled with mild detergent, then pressed through rollers, and repeated three or four more times.
Carding. Think big comb with steel bristles. The matted wool is passed through large steel rollers which produce a thin fluffy wool sheet, about 1.5 metres wide.
Combing. If the wool is being made into worsted yarns, it is combed as well. This process eliminated shorter strands and causes the hairs to lie parallel to one another before spinning.
Spinning. Fluffy ribbons of wool fibers are then spun into yarns. Woolen yarns are spun with less of a twist, while worsted yarns are spun tighter.
Bleaching & Dyeing. Wool can be bleached and dyed at various stages of the process.
Other key terms.
Virgin Wool. Does not refer to the sexual inexperience of a sheep. Instead, it refers to wool that is all-new and has no recycled wool in it. Recycled wool is inferior in quality. Sometimes used to refer to the first shearing of a sheep as well.
Merino wool. Wool gained from the Merino sheep. Used widely in Australia and New Zealand.
Cashmere wool. Wool gained from the Kashmir goat. Native to various Asian countries.
Angora wool. Wool gained from the Angora rabbit. Not be confused with Mohair, which is wool from the Angora goat.
Lambswool. Wool gained from the first shearing of a sheep, at around seven months of age. Prized for its softness.
Fun Fact. In an effort to boost the wool industry in 15th century Britain, a law was put in place that every person over the age of seven must wear a wool cap outside the house. In addition, women were obligated to wear wool flannel as undergarments and the dead were decreed to be buried in wool shrouds. These offenses were punishable with half a week’s wages.
For this entry, I have to give much credit to the book, "Hand book of Textile Fibres: Natural Fibres" by Gordon Cook.