Horsehair

When I say "horsehair', the tail and mane of a horse as well as the "tuft' at the end of a cow's tail are sources that I think of. There probably are other animals that have the same type of slick, stiffish hair, but horses' tails are the only ones to have fibers long enough to weave with without spinning.

What properties does it have?
Being hair, it is a protein fibre, so it has more or less the same properties as other protein fibres. Being harder and stiffer means it takes longer to absorb water, and it takes considerably more work to felt (but it does). It can be dyed with dyes suitable for protein fibres.

What has it been used for?
In Scandinavia, peasants and fishermen have mostly used it spun for ropes, for fishing lines (possibly plaited), for milk sieves, fishing mittens, outer socks, horse reins and horse rugs. Unspun it has been used for flour sieves and brushes.

Upholstery fabrics with horsehair as weft has primarily been used by the wealthier classes, and (I guess) the same went for "stiffening fabrics" as in men's coats and crinolines, (which happens to mean "horsehair and linen").

What is horsehair used for today?
Brushes and stuffing are the most common uses today. Upholstery fabric is woven industrially in France and Great Britain.
- FiberArts.org