Methods and cosmetic compositions are disclosed for applying a desired shape to keratin fibers, preventing or reducing frizzy appearance of hair, improving color retention of artificially colored hair, and improving the aesthetic appearance of hair. Methods for using cosmetic compositions according to the invention are silica sol-gel compositions comprising a homogeneous dispersion of (a) epoxysilane-functionalized silica particles (b) a cosmetic particulate such as PTFE and (c) a polysaccharide, such as chitosan.