Utoto wa asidi ndi anionic, umasungunuka m'madzi ndipo umagwiritsidwa ntchito kuchokera kumadzi a acidic.Utoto uwu uli ndi magulu a acidic, monga SO3H ndi COOH ndipo amagwiritsidwa ntchito pa ubweya, silika ndi nayiloni pamene mgwirizano wa ionic umakhazikitsidwa pakati pa protonated -NH2 gulu la fiber ndi gulu la asidi la utoto.