Hessian

A cloth woven from jute and usually shipped in bales. Bales of hessian cloth having internal yellow stains may have the appearance of contamination by salt water. These stains may be due to the thread used in the manufacture, which although of good quality, leaves patches of deep yellow colour, without in any way affecting the quality of the hessian. However, yellow staining does occur if hessian has been wet for some time – if such staining is in the middle of a bale without any direct link to external damage it could indicate dampness of cloth prior to baling. In such cases a fresh water reaction would result from silver nitrate test.

See IMDG Books in class 4.2 under Fabric, Vegetable (no UN No. assigned).
Although absolutely clean and dry and not subject to the provisions of the IMDG Code, hessian fabric can easily be ignited in contact with oxidizing agents, particularly liquids and may give rise to spontaneous combustion in contact with animal or vegetable oil. Hessian fabric is used as "backing" in the carpet industry.
The large rolls should be handled and stowed with care to avoid deformation.