A mixture for forming a coating on a surface includes a metal alkoxide having the chemical formula Si(OR.sup.1).sub.4, OR.sup.1 being a hydrolysable group, an organoalkoxysilane having the chemical formula R.sup.2.sub.xSiOR.sup.1.sub.(4-x), R.sup.2 being an epoxy group and x being an integer from 0 to 3 , a silica filler, and an organic acid for promoting hydrolysis and cross-linking the metal alkoxide and the organoaloxysilane. A coating on the surface is formed by depositing the mixture on the surface to form an under layer and depositing an outer layer comprising primarily a radiation activated self-cleaning material on the under layer. The radiation activated self-cleaning material can include titanium dioxide (TiO.sub.2) particles at least partially in anatase form.