Microemulsions are provided in which the oil phase comprises a reaction product of an organosilicon compound having amino groups and an organosilicon compound having epoxy groups, wherein the reaction product has at least one amino group and two silicon-bonded -OR groups. A method for making the micro­emulsions which comprises reacting the two organosilicon compounds sufficiently to allow the reaction of some of the amine groups with the epoxy groups, but avoiding the excessive crosslinking of the components and their application in the treatment of fibrous materials is also described.