Decortication
Also searched as: decorticate, decorticator, decorticating, hurd separation, fibre extraction, raspador
Decortication mechanically strips fiber from the surrounding plant tissue: the woody core of bast stems such as hemp and kenaf, or the fleshy pulp of leaves such as sisal.
In detail
The word means removing the outer layer, and in fiber processing it has two related uses. For bast crops, a decorticator breaks the stalk and separates the fibrous outer bast from the woody inner core, called hurd or shiv, often from dry stems that are not fully retted. For leaf fibers such as sisal, which are not normally retted, rotating drums with blades scrape away the soft leaf tissue to free the fiber strands, which are then washed and dried. Ramie is decorticated into ribbons that still need chemical degumming.
The science and numbers
In bast stems, fiber bundles lie in the outer tissue, outside the woody core, and are attached to it by pectin-rich tissue. Mechanical decortication applies crushing, bending and impact through fluted rollers, hammers or beaters, so the brittle core fractures while the flexible fiber survives. High-speed hemp decorticators separate hurd from fiber in continuous lines. For sisal and similar leaf fibers, decortication is the main extraction step. Decorticated ramie retains substantial gums and is chemically degummed, typically with hot alkali, before spinning. Outcomes depend on stem moisture, degree of retting and machine settings, with fiber damage traded off against cleanliness.
A practical example
A hemp farm sends dried stalks to a decortication plant, which returns two streams: bales of bast fiber and woody hurd sold for animal bedding or building materials. A textile buyer asks whether the stalks were retted first, because unretted, decorticated fiber is coarser and more gum-bound and would need further processing before it could be spun into fine yarn.
What to distinguish
Decortication is not retting: it separates tissues mechanically rather than breaking down pectin biologically. Fiber decorticated without retting is often suited to industrial uses unless it is further degummed or cottonized. The word is also used in medicine and grain milling with unrelated meanings, and it tells you nothing about fiber fineness or quality.
Origins and history
Built on the Latin cortex, meaning bark, decortication has long meant removing bark, husk or rind. Machine decorticators for fiber plants were developed in the nineteenth century, including early hemp machines in Italy, and mechanical decortication became the standard way to extract sisal. Interest in hemp decortication revived as several countries again permitted industrial hemp cultivation, creating demand for continuous, high-throughput lines.
Related terms
Sources & further reading
- Merriam-Webster: Decortication
- ScienceDirect Topics: Fibre extraction
- USPTO: Patent 4568739, Method for degumming decorticated plant bast fiber
- Google Patents: US7669292B2, Decortication process
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.