Harmonized Tariff Chief Weight Adjustments under Variable Regain Rates
Harmonized tariff chief weight declarations require converting oven-dry fibre masses into commercial mass using statutory regain allowances to prevent reclassification.
Wool Regain Rate
Natural Hydration
A standardized percentage defines the mass of water that sheep fibre holds when in equilibrium with a specific atmosphere. The wool regain rate is officially set at 13.6 percent for scoured material, which is much higher than for most other fibres. This value maintains the financial accuracy of the transaction by accounting for moisture weight.
Hygroscopic Property
Excellent insulation and comfort stem from the ability of the fibre to absorb large amounts of vapour without feeling damp. Because the wool regain rate is so high, the material can release heat when it absorbs moisture, protecting the wearer from sudden temperature changes. The internal water also acts as a natural flame retardant.
The hygroscopic nature of the material ensures that it can buffer the microclimate between the skin and the garment, providing warmth in winter and cooling in summer.
Commercial Settlement
Transactions in the global market use the dry weight plus the official regain to determine the final invoice amount. Testing laboratories verify that a bale matches the expected wool regain rate by comparing the oven-dry mass to the original mass. If the actual moisture exceeds the standard, the price is adjusted downward to account for the difference.
Processing Influence
Flexibility and spinning performance depend on the amount of water held within the fibre structure. Maintaining the wool regain rate at a consistent level prevents brittleness and breakage during the carding and combing stages. Humidity control in the mill is therefore necessary for high-quality yarn production.