The invention relates to self-cleaning synthetic bodies, obtained as follows: a) a siloxane coating (a) is applied to a synthetic substrate and cured, b) the polar fraction of the surface energy of the cured siloxane coating on the substrate is increased to a value of at least 10 mN/m and c) a coating (b) containing photocatalytically active TiO2 particles is applied to the synthetic substrate and cured.