wt y is about 5 30 wt and z is about 1 30 wt z is c 12 alkyl quaternized monomer the weight average molecular weight of the terpolymer is 200 000 to 2 000 000 preferably 400 000 to 800 000 it is water soluble or water dispersible and forms a clear humidity resistant hydrophobic film when cast upon a support surface which is surface active and hydrolytically stable and is a homogeneous terpolymer cosmetic compositions of advantageous properties including about 0 1 to 10 by weight of the terpolymer can be prepared conveniently in this invention preferably the homogeneous terpolymers of the invention are made according to the method described by kou chang liu et al in u s pat no 5 626 836 the preparation of dodecyldimethyl methacryloimidopropyl ammonium tosylate dmapma c 16 ts a mixture of 360 g of dodecyl tosylate and 200 g of dmapma were slowly heated up to 70 u00b0 c without a solvent stirring was continued at 70 u00b0 c for 2 hours then the reaction was cooled to room temperature and solidified product was further used in polymerization without purification n vinylpyrrolidone vp 280 g and deionized water 1400 g are charged into a 2 liter resin pot equipped with a gas inlet liquid inlet.