felt

Felt comes from Old English felt, from Proto-Germanic *feltaz, possibly from Proto-Indo-European *pel- (to press, to drive). Cognates include Dutch vilt, German Filz, and Old Norse filt. The word names both the material and the process: felting is the matting and pressing of fibers (usually wool) into a dense, non-woven sheet. No spinning, no weaving, no knitting. Just moisture, heat, pressure, and agitation.

Felt may be the oldest textile technology. Nomadic peoples of Central Asia — the ancestors of the Mongols, Turks, and other steppe cultures — used felt for yurts (ger), clothing, saddle blankets, and boot liners. The yurt is a felt tent. The entire dwelling is wrapped in thick felted wool. Marco Polo described Mongol felt tents in the 13th century. The technology was already ancient by his time.

Felt works because wool fibers have microscopic scales on their surface. When wet, heated, and agitated, these scales interlock irreversibly. The fibers tangle. They cannot be untangled. This is why wool sweaters shrink in hot water — accidental felting. The process is permanent. A felted fabric cannot be returned to its original state. Unlike woven or knitted fabrics, which can be unraveled, felt is a one-way transformation.

The word felt generates the compound 'felt-tip' — felt-tip pens use a pointed piece of pressed felt to deliver ink. Hat-making historically depended on felt (a felt hat is called a fedora, a trilby, or a bowler depending on its shape). The phrase 'mad as a hatter' comes from mercury poisoning among hat felters in the 18th and 19th centuries — mercury nitrate was used to process fur felt.