Bast fiber
Also searched as: bast fibres, stem fiber
Fiber obtained from the stem tissues of plants such as flax, hemp and ramie.
In detail
Bast describes where a fiber occurs in a plant. Flax and hemp provide bundles of strong supporting fibers in their stems. Processing separates those bundles from surrounding tissue and woody material before preparing them for yarn. A textile strand may still contain several associated cells, so a visible strand is not necessarily one elementary fiber.
The science and numbers
Bast fibers are hierarchical composites. In flax the elementary fibers are single plant cells with a polygonal cross-section, roughly pentagonal to octagonal, averaging about 15 to 18 micrometers across, each with a thick cellulose-rich secondary wall and a narrow lumen. Pectin and hemicellulose cement overlapping cells into technical bundles, and cellulose microfibrils lie close to the fiber axis, which gives high stiffness and low extension. Composition separates the crops: flax fiber is reported at roughly 64 to 78 percent cellulose with about 2 to 5 percent lignin, long hemp bast at about 55 to 72 percent cellulose and 2 to 5 percent lignin, while jute carries about 12 to 14 percent lignin, which makes it stiffer and prone to yellowing in light. Transverse dislocations called nodes or kink bands help microscopic identification, but flax and hemp are hard to tell apart and laboratories combine drying-twist tests, lignin staining and spectroscopy.
A practical example
A linen shirt starts with a stem-derived fiber; a cotton shirt starts with seed hairs. Both contain cellulose, but their extraction and preparation routes differ. This distinction helps explain why a flax journey includes retting and scutching while a cotton journey includes ginning.
What to distinguish
Bast is a botanical category, not a guarantee of softness, organic cultivation or low impact. Ask which plant, preparation method and finished construction the description refers to.
Origins and history
Bast fibers may be among the oldest textile materials, but the evidence is contested. In 2009 researchers reported fibers from Upper Paleolithic layers of Dzudzuana Cave in the foothills of the Caucasus, Georgia, radiocarbon-dated in part to about 32,000 to 26,000 years before present, and described them as wild flax, some spun, dyed and knotted. A published comment in 2010 argued that microscopy and the presence of nodes were not sufficient to identify the fibers as flax. The exchange illustrates why bast identification still relies on combining several methods.
Related terms
Sources & further reading
- Alliance for European Flax-Linen & Hemp: Flax growing and expertise
- Alliance for European Flax-Linen & Hemp: Textile applications of hemp
- Science: 30,000-year-old wild flax fibers (Kvavadze et al., 2009)
- Science: Comment on '30,000-year-old wild flax fibers' (Bergfjord et al., 2010)
- PubMed: The development, differentiation and composition of flax fiber cells
- Cellulose (Springer): Extraction of cellulose fibers from flax and hemp, a review
Technical references reviewed 2026-09-22. Examples are illustrative. Industry organizations and manufacturers describe their own fields; their references are not independent product endorsements. Figures are approximate and depend on the stated test conditions.