Linen is made from fibers harvested from the flax plant. After the flax plants are harvested, they need to be retted to dissolve the pectin that keeps the bundles of fibers attached to the core of the stem. Retting can be done by leaving the stems exposed to the weather for several weeks (the dew and rain will remove the pectin) or by soaking the stems in a river or stream.
Once the stems are retted and the bundles are loosened, the plants are beaten with a stick or other tool to crush the tough core of the stem.
The fibers, including the linen flax, remain intact and are then drawn through a heckling comb to align all of the fibers than can be spun into cloth.
Now that you know how it's made, check out a finished product for yourself, like this beautiful two-toned linen scarf
handwoven in India!