The invention provides a method for inhibiting color fading in color-treated keratinous fibers, which method includes treating the keratinous fibers with a color-fade inhibiting-effective effective amount of a monoalkyl quaternary ammonium salt. The invention also provides a method for enhancing the intensity of color in color-treated keratinous fibers, which method includes treating the keratinous fibers with a color intensity enhancing effective amount of an alkyl a quaternary ammonium salt. Additionally provided are products for inhibiting the fading of color and increasing the intensity of color in color-treated keratinous fibers.
