Wool suit fabric is popular for men and women, thanks to its breathability, durability and ease of wear. Wool quality is judged by the thinness of the wool fiber, measured in microns (one micron is one-millionth of a meter). The thinner the fiber, the more desirable the wool suit fabric–and the more comfortable it is to wear. The best-quality wool comes from Merino sheep, bred in climates that cause the sheep to produce thin-fiber wool.


People have been wearing garments made of wool for thousands of years. The wool trade was an important commercial feature in the development of Babylonia, Greece, Britain and Australia. Originally used for blankets and shawls, wool became a clothing staple during the medieval period, when weavers and dyers used it to create jackets, hats and stockings. The industrial revolution in the 19th century sped up the production of wool clothing, making it more affordable and readily available.


Wool fibers are made up of layers; the outside is called the cuticle and the inside is called the cortex. The cuticle is covered with a waxy protein that causes water to bead easily on its surface, making it great for winter outerwear. Water strikes the exterior of the fabric, but rarely penetrates it before rolling away. The materials in the fiber’s cortex are able to absorb around 30 percent of their weight in moisture. Since wool is an all-natural material, absorbed perspiration can evaporate quickly, leaving you dry and comfortable.


Wool responds to changes in your body temperature. It insulates you when it’s cold outside and helps wick moisture from your skin if you sweat. Also, wool fibers are more elastic than other fibers. They stretch and move with you, but when returned to the hanger, they’ll regain their shape.


Wool fabric can be woolen or worsted. The difference is in whether the fibers are combed for smoothness. Woolens are not combed, leaving them with a thick, plush pile. Worsteds are combed, making them smooth and lighter in weight. Most suit fabric is worsted to make it suitable for year-round wear and better suited to close-fitting tailoring.


Many people think wool suit fabric is scratchy and hot, but this isn’t the case when clothing is made from fine grades of wool. Merino wool, for example, has fine fibers that make it softer than traditional wool. Its micron measurements are between 18 and 24, compared to a range of 25 to 32 for most knit sweaters. The finest grades of Merino are as small as 13 microns, making it comparable to cashmere (approximately 14 microns).