Mechanism of fatty soil removal

The effects of temperature, detergents, electrolyte, agitation and fabric structure on the removal from cotton of octadecane, tripalmitin, stearyl alcohol and stearic acid labelled with carbon‐14 have been studied. The following mechanisms appear to be operative in the removal of these materials: (1) the rolling‐up mechanism; (2) mesomorphic phase formation; (3) soap formation; (4) break‐up of polycrystalline aggregates. In general, the addition of electrolyte in the presence of surface‐active agents increases the amount of fatty soil removed. The magnitude of the electrolyte effect depends on (a) the degree of ionisation, (b) the pH of the solution and (c) the valency of the added cation. By means of a chopped fibre technique it has been possible to show that about 35% of the fatty soil is held on the surface of the threads, about 30% between the fibres of which the threads are composed, about 30% inside the tubular fibres while about 5% is held in the fibrile structure of the fibres.