Standardisation Frame
International standardisation documents establish the methods used to test and calculate the commercial mass of textile fibres during trade transactions. Known broadly as the bisfa rules, these guidelines are maintained by the International Bureau for the Standardisation of Man-Made Fibres to provide a common basis for determining moisture regain and commercial weight. Flax spinneries and export houses utilise these specific parameters to calculate the invoice weight of linen shipments from processed bundles.
By standardising the dry weight determination and the subsequent addition of official moisture allowances, the guidelines prevent disputes arising from ambient humidity shifts during maritime transport.
Commercial Allowance
Moisture levels in bast fibres fluctuate constantly during storage and shipping, making an established reference essential for financial settlement. Flax has a standard moisture regain percentage defined under the bisfa rules that traders use to adjust the raw scale weight of a shipment to its official commercial weight. The calculation uses the oven-dry weight of the fibre lot, to which the designated percentage allowance is added.
This ensures that buyers pay for actual fibre mass rather than water absorbed during transit.
Laboratory Procedure
Testing laboratories process representative samples drawn from shipment lots using heated ventilated ovens. Workers weigh the sample before and after drying to a constant mass at one hundred and five degrees Celsius. This laboratory method is executed before spinning or export, and the resulting certificate of weight acts as the legally binding commercial document between Chinese flax mills and international buyers.
