Linen is a bast fiber. Flax fibers vary in length from about 25 to 150 mm (1 to 6 in) and average 12–16 micrometers in diameter. There are two varieties: shorter tow fibers used for coarser fabrics and longer line fibers used for finer fabrics. Flax fibers can usually be identified by their “nodes” which add to the flexibility and texture of the fabric.
The cross-section of the linen fiber is made up of irregular polygonal shapes which contribute to the coarse texture of the fabric.