Commercial Weight Recalculation Methods for Raw Textile Fiber Import Lots
Commercial weight recalculation adjusts raw fiber invoice mass by adding official contractual moisture regain allowances to laboratory verified oven-dry fiber mass.
Polyester Moisture Allowance
Standard Correction
A commercial weight percentage adjusts the transaction mass of polyester shipments to account for a standardised quantity of absorbed water. Polyester moisture allowance is officially set at a low value of zero point four percent of the bone-dry mass of the fibre. This low percentage reflects the hydrophobic nature of the synthetic polymer, which absorbs very little water compared to natural fibres.
Buyers and sellers apply this allowance to ensure that weight measurements are standardised across different storage conditions.
Commercial Standard
Trade contracts use this value to calculate the billing weight from the oven-dry weight of the shipment. This practice removes any variance caused by atmospheric exposure during transit or warehousing. The calculation protects the buyer from paying for excess moisture that the polymer may have absorbed in highly humid environments.
Analytical Testing
Oven drying of representative samples isolates the dry polymer mass for commercial calculation. The specimens are dried at one hundred and five degrees Celsius until they reach a constant mass. The standardised allowance percentage is then added to this dry weight to determine the invoiced quantity.
Processing Impact
Low moisture retention in polyester reduces the need for extensive pre-spinning drying compared to nylon. It also prevents fungal growth during long maritime transport.