According to the invention disclosed herein wool sliver may be effectively shrinkproofed by immersing the sliver continuously into a bath of shrinkproofing solution to a depth of at least 1 meter if said sliver is carried down into said solution within 10.degree. of vertical. According to the invention the most useful solution is an aqueous solution into which chlorine gas has been aspirated. An apparatus according to the invention comprises a substantially U-shaped bath having a depth exceeding 1 meter and equipped with means to convey wool sliver into said bath within 10.degree. of vertical.