Jute Fibre

Two species are grown and they are traded as distinct types. Tossa jute (Corchorus olitorius) gives a softer, stronger, silkier fibre and accounts for most of the crop; white jute (C. capsularis) is coarser and paler but tolerates the standing water of low-lying land where tossa struggles. Buyers specify the type, because the fibre properties are different enough to matter to a spinner.

The near-monopoly geography follows from what the crop needs after harvest as much as during growth. Retting jute requires large volumes of clean, slow-moving water at a warm temperature, available exactly when the crop is cut. The delta provides this; most places do not, and that is a large part of why the industry has never dispersed.

Cut jute stems are bundled and submerged in ponds, ditches, or slow channels, weighted down to keep them under. Over the retting period, microbial action loosens the bond between the bast and the woody core. The retting judgement is the classic one for a bast fibre — stop too early and the fibre will not come away, leave it too long and the fibre itself is attacked, losing strength and darkening — but jute adds its own difficulty: the water itself affects the outcome, and retting in muddy or stagnant water stains the fibre irrecoverably.

Stripping is then done by hand. A worker standing in the water takes the retted stems, breaks the base, and pulls the fibre away from the core in long ribbons, washing it as it comes. This step has resisted mechanisation stubbornly, and it is the reason jute production remains labour-intensive and smallholder-based. The stripped fibre is washed, then sun-dried hanging over bamboo racks, and the drying stage strongly influences the final colour and lustre that the grade will turn on.

Raw jute is graded in the producing countries under national standards that separate the tossa and white types and rank lots by named grades. The assessment is a hand-and-eye craft: colour and lustre, strength, fineness, length, and the amount of hard, woody root end left on the fibre. Root content matters commercially because those butt ends will not spin and must be cut away, so a lot heavy in roots contains less usable fibre than its weight suggests.

• Excessive hard root ends (the butt of the stem)
• Specky and knotty fibre from incomplete retting
• Runners — fibre still bound together in strips
• Discolouration and staining from muddy or stagnant retting water
• Weak fibre from over-retting
• Croppings and short lengths reducing spinnable value

Grade names and their definitions belong to the national standards of the producing countries and to the contracts that invoke them; they are versioned and are not reproduced here. Below the graded fibre sits jute cuttings — the coarse, rooty ends cut off — which are traded separately for paper and coarser products.

Jute goes to sacking and hessian, to carpet backing, to twines and cordage, and — a market that has grown as the packaging one has eroded — to geotextiles, where a fibre that is strong at first and then rots away is exactly what is wanted for erosion control while vegetation establishes. Synthetic packaging displaced much of the traditional sack trade, and the fibre’s biodegradability has since become one of its principal selling points.

Trade moves in two forms: raw jute in pressed bales, and manufactured jute goods from mills in the producing countries. Some governments in the region maintain policies that reserve certain packaging uses for jute, so the demand side of this commodity is shaped by regulation as well as by price and substitution.