Moisture Content
Moisture content in animal fibers is calculated as the amount of water a fiber holds when it reaches equilibrium with the atmosphere. Because wool is highly absorbent, the wool regain directly affects the commercial weight and the physical properties of the yarn. Standardized values are used in trade to ensure that buyers pay for fiber rather than fluctuating water content that might be introduced during storage in humid environments.
Commercial Calculation
Trading houses use a legal standard of around thirteen to fifteen percent to normalize the weight of a shipment. If the actual wool regain measured in the warehouse is higher than the standard, the invoice weight is adjusted downward. This system prevents the seller from gaining an unfair advantage by shipping damp wool.
Physical Property
Fiber diameter and elasticity vary depending on the amount of moisture the polymer contains. As the wool regain increases, the fibers become more flexible and easier to process through the spinning frames. Controlling the humidity in the mill environment is therefore necessary to maintain consistent yarn quality and machine performance.
Testing Procedure
A sample of the wool is heated in a specialized oven until all moisture is removed to determine the dry weight. Comparing this result to the original mass provides the wool regain value for the entire lot. Accurate testing requires hermetically sealed containers to prevent moisture loss or gain during transport to the laboratory.
