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.