Determination of Bast Fiber Fineness via Standardized Low-Pressure Air Permeability
Low-pressure air permeability tests determine bast fiber fineness by measuring specific surface area across standardized compressed fiber plugs under ISO 2370.
Fiber Moisture Regain
Moisture Ratio
Physical proportion represents the percentage of water held by dry textile material under specific temperature and humidity conditions. In flax processing, fiber moisture regain acts as a standard metric to calculate both the commercial shipment weight and the mechanical response during yarn drawing. For flax fibers, the standard value is traditionally set at twelve percent, which differs from that of cotton or synthetic alternatives.
Spinning Performance
Fiber flexibility depends heavily on this internal water content, which lubricates the cellular structure of bast fibers during drafting. When the level is too low, the flax fibers become brittle and prone to breakage on the spinning frame, causing frequent machine stoppages and uneven yarn. Conversely, excess water generates mold risks in packed bales and leads to slippage in the draw zone, where the rollers fail to grip the damp bundles.
This mechanical behavior directly dictates the relative humidity settings maintained in Chinese linen spinning rooms.
Commercial Weight
Invoicing procedures use the official standard value to adjust the invoiced mass of raw shipments. Sellers calculate the dry weight of the flax batch by heating a test specimen until its mass becomes constant, and then they add the agreed standard allowance.