Solvent Extraction Methods for NonFibrous Additives in Spun Yarns
Solvent extraction isolates spin finishes and waxes from spun yarns, preventing excess processing aids from inflating commercial mass and landed duty costs.
Lanolin Residual
Surface Impurity
Concentration of natural wool grease remaining on the fibre surface after the completion of the scouring process. Presence of lanolin residual indicates the thoroughness of the cleaning cycle and the readiness of the wool for subsequent dyeing or spinning. High concentrations interfere with the even absorption of dyes and the adhesion of chemical finishes.
Processing Consequence
Fibres that carry excessive grease tend to stick to the carding pins and cause uneven drafting in the spinning frame. The lanolin residual acts as a lubricant that reduces friction too much, leading to weak yarn or slippage during high-speed production. Conversely, removing every trace of grease can make the wool brittle and prone to static buildup.
Optimal levels are usually kept within a tight percentage range specified by the spinning mill. Laboratory reports provide the precise extraction weight to guide these adjustments.
Testing Verification
Solvent extraction using petroleum ether or dichloromethane is the standard way to measure the fat content. This quantitative test ensures that the scouring line is operating within the parameters required for premium quality.
Limit Specification
Acceptable limits vary based on whether the wool is destined for worsted or woollen processing. Excessive lanolin residual is often a cause for lot rejection in premium apparel contracts.