JUTE FIBER - Is apt to lose strength if exposed for a prolonged period to the action of salt water in a confined space. When jute cloth (in bale form) becomes wet, a chemical action may take place which sets up a considerable amount of heating, when the cloth naturally deteriorates and in some cases will rot to such a degree as to render it to powder. Country damaged bales of jute may be externally discolored in places, the bales often showing small stains only, but on opening the bales it may be found that the damage has spread badly in the middle, the jute being friable and dry. When bales are dispatched wet the rope lashings may burst. Although bales may be outwardly dry to the touch, latent moisture may set up dry rot in the heart of the bales, powdering the fiber.
If moisture penetrates the bales to any extent it causes mold, discoloration, and deterioration of the fibers. The damaged part can, as a rule, be used for inferior bags, or an inferior stuffing (mattresses, etc.)
Jute is the spinnable bast fiber, of an average length of 1.50 - 3 m, obtained from the jute plant. Jute belongs to the linden family (Tiliaceae).
These annual plants grow to 2 - 3 m in height with a stalk 2 - 3 cm in diameter.
Like flax, jute is usually obtained by cold water retting, which takes 10 - 20 days, followed by washing and drying. Jute is the most important natural fiber plant alongside cotton and, with flax and hemp, among the top three stalk fibers. The fiber's high lignin content (approx. 12%) means that it is brittle, loses tensile strength on exposure to light and has little resistance to moisture and acids. Jute is the most highly hygroscopic natural fiber.
Jute fibers have a polygonal cross-section of variable size, the lumen being of variable width.
Cuttings are the trimmed 15 - 40 cm long ends of the jute fiber; they are also commercially available under this name. "Meshta" is a somewhat coarser fiber from Thailand, very similar to jute and also known as "kenaf".
Jute from East Pakistan - In the jute trade a seller is allowed to deliver to a buyer, if shipment is made during July, August, and September, fiber containing 12% excess moisture, thereafter the seller is only allowed to deliver fiber containing 10% excess moisture. In the event of dispute it is customary for a board of arbitration to be set up consisting of senior members of the jute trade. The percentage of excess moisture in a parcel is decided by handling the jute itself and, although this may appear to be an antiquated method, it is understood that in practice comparatively accurate results are achieved.
Some mills have small electric ovens; they weigh the jute, bake it comparatively dry, and then leave it for twenty-four hours to re-assimilate natural moisture before weighing. They then claim the difference between the first weight and the weight after re-weighing as excess moisture and deduct this from the sales bill. This method is recognized to produce absolutely accurate results, but it is understood very few sellers will agree to sell on this basis. A further method of assessing the moisture content is by means of an American machine with four prongs which are driven into the center of a bale, the moisture content being registered on a dial.
Jute can be baled with anything up to 30% excess moisture and still appear dry on the surface. It is believed that any heart damage, which is attack within the bales and occurs only when the jute is abnormally damp, is due to excess moisture which has probably been added to the jute deliberately. If this is done skillfully, the only certain method of detection is for the bales to be opened and the fiber inspected.
Fire - It is now thought that jute is not subject to spontaneous combustion. In fact, it is believed that in many cases fires were due to human action, the most common method being to place inside a bale a mixture containing cow-dung and sulphur. According to the experts, it is difficult to say how long this will take to set fire to the jute, but sooner or later it ignites. There have been fires on ships attributed to spontaneous combustion, but it is thought that in these cases the bales work loose in stow, fire eventually being caused by the consequent friction. Jute, especially Indian jute, is, however, highly combustible, and should be treated as a hazardous cargo.