Abstract: A thin film on a surface of a solid substrate, including: a) spraying on the surface: —a colloidal suspension including solid nanoparticles (or colloids) of an inorganic compound dispersed in a solvent to obtain a wet layer of the colloidal suspension on the surface; or —a suspension including an inorganic compound in polymeric form in a solvent, to obtain a wet layer of the suspension of the inorganic compound in polymeric form on the surface; or —a solution or suspension of an organic polymer in a solvent, to obtain a wet layer of the solution or suspension of the organic polymer on the surface; b) drying the wet layer; c) optionally, heat-treating the wet layer that has undergone the drying step, whereby the thin film is obtained; wherein: the solvent comprises at least 95% by weight of water, and the drying is carried out in a static atmosphere.