Flannel is a soft woven fabric, of varying fineness. Flannel was originally made from carded wool or worsted yarn, but is now often made from either wool, cotton, or synthetic fiber. Flannel is commonly used to make tartan clothing, blankets, bed sheets, and sleepwear.
Flannel may be brushed to create extra softness or remain unbrushed. Brushing is a mechanical process wherein a fine metal brush rubs the fabric to raise fine fibres from the loosely spun yarns to form a nap on one or both sides. If the flannel is not napped, it gains its softness through the loosely spun yarn in its woven form.
The term "flannel shirt" is often mistakenly used to refer to any shirt with a plaid or tartan pattern. However, 'flannel' refers simply to the fabric, and not all flannel shirts are plaid.
The origin of the word is uncertain, but a Welsh origin has been suggested as fabric similar to flannel can be traced back to Wales, where it was well known as early as the 16th century. The fabric was called ''Welsh cotton'', and despite its name, it was a coarse woolen material with a fluffed surface similar to flannel.
The French term flanelle was used in the late 17th century, and the German Flanell was used in the early 18th century.
Flannel has been made since the 17th century, gradually replacing the older Welsh plains, some of which were finished as "cottons" or friezes, coarse woolen cloth that was the local textile product. In the 19th century, flannel was made particularly in towns such as Newtown, Montgomeryshire, Hay on Wye, and Llanidloes. The expansion of its production is closely associated with the spread of carding mills, which prepared the wool for spinning, this being the first aspect of the production of woollen cloth to be mechanised (apart from fulling). The marketing of these Welsh woollen clothes was largely controlled by the Drapers Company of Shrewsbury.
At one time Welsh, Yorkshire, Lancashire and Irish flannels differed slightly in character due largely to the grade of raw wool used in the several localities, some being softer and finer than others.