Determining True Dry Fiber Mass through Laboratory Solvent Extraction Procedures
True dry fiber mass requires quantitative solvent extraction of non-fibrous processing aids prior to forced-draft oven drying to constant weight.
ISO 3074
Method Framework
International standardized test protocols regulate the quantitative extraction of fatty and waxy substances from combed wool sliver using organic solvents. Under ISO 3074, test laboratories determine residual grease levels on top-processed wool to verify scouring efficiency and lubricant application. The procedure measures dichloromethane-soluble matter to evaluate clean wool purity after carding and combing.
Extraction Procedure
A weighed wool sample undergoes Soxhlet solvent extraction using dichloromethane for a fixed number of siphon cycles. The solvent dissolves natural wool grease and residual processing lubricants present on the fibers. Following solvent distillation, remaining non-volatile lipid residue undergoes oven drying at controlled temperatures before precise balance weighing.
The mass fraction of extracted matter is calculated relative to the oven-dry mass of the wool specimen. Using dichloromethane isolates non-polar fats without dissolving water-soluble suint or proteinaceous wool fibers.
Practical Scope
Test results from the method guide top-makers in adjusting scouring bowl detergent dosing and comb oil spray nozzles. The standard applies specifically to combed wool sliver, excluding raw greasy wool and spun yarn structures.
Commercial Specification
Commercial contracts for wool top dictate strict upper boundaries for solvent-extractable matter to prevent downstream yarn spinning problems. Excessive residual grease causes drafting slip and roller lapping, while insufficient grease causes static electricity generation and fiber breakage during worsted drawing.