Determination of Wet Spun Flax Yarn Linear Density and Mechanical Properties
Wet spun flax linear density and mechanical properties depend on strict moisture regain control, hot water pectin drafting, and CRE tensile evaluation.
Hot Water Drafting
Fibre Attenuation
Mechanical stretching of flax slivers within a heated liquid medium allows for the production of fine, high-tenacity yarns. Hot water drafting is the central process in wet spinning where the roving is drawn through a bath at approximately sixty degrees Celsius. This heat softens the natural pectins that bind the individual flax fibres together.
As the pectins soften, the fibres slide past one another more easily to create a thinner strand.
Pectin Softening
Controlled temperature in the drafting zone ensures that the fibre bundles separate into their constituent ultimates without breaking. If the water used in hot water drafting is too cold, the fibres remain clumped and the resulting yarn is coarse and uneven. Conversely, excessive heat can degrade the fibre strength or cause the drafting rollers to slip.
Spinning technicians monitor the bath temperature constantly to maintain the delicate balance required for fine linen.
Yarn Uniformity
Smooth attenuation of the flax roving leads to a consistent linear density throughout the length of the yarn. Implementing hot water drafting allows Chinese mills to produce the 60s and 80s lea counts required for luxury shirting. The process removes many of the slubs and irregularities that characterize dry-spun linen.
It is the primary method for achieving the high level of yarn evenness demanded by modern high-speed looms.