an air oven at 90 u00b0 110 u00b0 c the dried tow contained about 16 17 wt of the surfactant inspection of the tow both as to its tactility and as to its visual appearance indicated that much of the surfactant remained on the surface of the filaments part a of this example was repeated except that the tow was exposed to steam at 120 u00b0 c for 2 minutes inspection of the tow both as to its tactility and as to its visual appearance indicated that substantially all of the surfactant had been diffused into the filaments two 120 kilotex 1 100 000 denier tows of never dried mpd i filaments prepared as described in part a of example 1 were creeled through the guides of the continuous tow dyeing apparatus described in part b of example 1 following the same general procedure of the example with the following exceptions the aqueous bath contained in a pool above the nip rolls was maintained at 80 u00b0 95 u00b0 c and was prepared by adding 128 4 kg 283 lbs of a 93 wt aqueous solution of isopropylammonium dodecylbenzenesulfonate salt mixture of isomers a water soluble anionic surfactant to 350 1 of hot 90 u00b0 95 u00b0 c water with only very mild agitation to minimize aeration of the solution the calculated concentration of the anionic surfactant was 25 4 wt the tows were passed through the nip rolls at a speed of 17 m min and.