Determining Standard Moisture Regain Values in Raw Textile Fibre Imports
Commercial mass calculations adjust raw import dock weights to certified oven-dry mass plus standard moisture regain values for exact invoice settlement.
Non Water Volatile Allowance
Moisture Calculation
The permitted weight percentage of non-aqueous volatile substances in raw or processed fibres is used to calculate commercial weights. In raw wool trading, the non water volatile allowance accounts for trace oils, solvent residues and processing lubricants that evaporate at high temperatures. This allowance is subtracted from the clean dry weight of the fibre batch.
It ensures that the transaction is based solely on actual wool mass.
Commercial Standard
International wool testing standards define the acceptable limits for these non-water volatile materials to prevent disputes between buyers and sellers. When test laboratories determine the clean yield of a wool lot, they apply the non water volatile allowance to correct for residual grease. If a lot exceeds this limit, the buyer is entitled to a price adjustment.
This practice maintains trust in the global wool market by standardizing the basis of commercial trade.
Laboratory Method
Oven drying and solvent extraction are used to separate water from other volatile substances in the wool sample. The sample is weighed before and after extraction to determine the quantity of grease and other non-aqueous matter. This method requires analytical balances that are calibrated to zero moisture regain.
The results are reported as a percentage of the total weight.
Process Impact
Excessive residual grease can interfere with the spinning and dyeing processes of the wool yarn. Sourcing teams monitor these levels to ensure that the fibre runs smoothly through the carding machinery.