Silica based coatings with various thicknesses (600-3000 mm) were prepared from the gellation of aqueous suspensions composed of colloidal silica particles, small graphite particles and inorganic binder materials, the latter were included to improve the coating structure. The graphite particles added in amounts of 0.8-3.6 wt.%, in the dried coating, absorb visible light with the same efficiency, which results in coatings with neutral optical density in this range of the spectrum. The optical density of the coatings can be changed from basically 0, in coatings without graphite, to more than 2 in thick coatings with 3.6 wt.% of graphite. The structural characterization of the coatings was carried out using X-ray diffraction, Raman scattering and atomic force microscopy.