Moisture Calculation
The standardized percentage of water content allocated to a dry mass of textile material to determine its commercial weight constitutes the basis for international trade. Conducting the ISO 6741 moisture regain test ensures that buying and selling weights are adjusted to a common moisture level of twelve percent for flax yarn. This standard prevents financial losses caused by the natural fluctuation of water content in linen during storage or transit.
By calculating the oven-dry weight and adding the agreed regain, mills establish a uniform invoice weight.
Testing Method
Laboratory execution of this standard involves heating the linen samples in a ventilated drying oven until they reach a constant mass. The test apparatus measures the weight of the sample before and after drying at a temperature of one hundred and five degrees Celsius. After the moisture is completely evaporated, the final dry weight is recorded as the baseline for the calculation.
This difference between the initial wet mass and the oven-dry mass reveals the actual moisture content of the lot. Multiplying the dry mass by the official regain percentage yields the correct commercial weight for the billing document. This calculation prevents billing errors because even small moisture deviations alter the shipping weight by several hundred kilograms on a container-sized shipment.
Trade Resolution
Commercial contracts for linen yarn specify this test as the final authority in cases of weight discrepancy at the port of discharge. Because relative humidity alters yarn weight during long sea voyages, moisture analysis provides a reliable method to verify the original shipment quantities. The test certificate accompanies the shipping invoice to guarantee that the buyer pays only for the actual fibre and the allowed moisture content.
