Felting and Flocculation of Natural Wool in Water and in Mixed Solvents

Shrinkage-time curves have been determined for untreated wool fabric in various water/dimethylformamide (DMF) and water/ethanol mixtures, using a Cubex machine. Felting shrinkage decreases drastically above 90% DMF and around 85% ethanol. In a qualitative way the shrinkage results correlate well with the decreased attraction between the wool fibers in the mixed solvents, as measured in flocculation tests of the chopped wool fibers. Root-to-tip variation of interfiber attraction for natural wool in water has been examined by the flocculation of parts of wool fibers cut from a single lock of oriented natural wool. The results indicate a decrease in hydrophobicity from fiber root to fiber tip, as expected, from increased oxidation in weathering.