Moisture Determination
Standardized test method for calculating the commercial mass of textile fibers determines the oven-dry weight after the removal of all loose moisture. This procedure of ISO 6741 dry mass ensures that transactional weights are calculated using a uniform basis for buying and selling raw fiber. Testing laboratories use this method to resolve disputes about the moisture content of yarn and fiber shipments.
The method stops being used once the fiber is processed into finished, coated garments.
Moisture Regain
Textile fibers naturally absorb moisture from the surrounding air depending on the relative humidity. To calculate the invoice weight, a standardized percentage called moisture regain is added to the ISO 6741 dry mass of the sample. This addition ensures that buyers do not pay for excess water absorbed during storage.
Laboratory Heating
Drying ovens operated at a temperature of 105 degrees Celsius are used to dry the samples until they reach a constant mass. This drying process removes all free water without damaging the polymer structure of the fiber. After drying, the ISO 6741 dry mass is recorded immediately using a closed balance to prevent the sample from reabsorbing moisture from the air.
Commercial Transaction
Raw fiber prices and shipping invoices are calculated directly from this corrected dry mass value. This ensures fair trade between spinning mills and fiber suppliers.
