The pyrosil process is a flame pyrolysis, with which a few nanometer-thin, amorphous, highly crosslinked silicate layer is produced on the substrate materials. The surface to be treated is guided through the oxidizing region of a gas flame, into which a silicon-containing substance, the "precursor", is metered. This results in a defined chemical structure on the substrate surface with important binding elements for the later adhesion of various materials. Thus, for example, the nanoporous structure of the silicate layer ensures better mechanical anchoring of the subsequently applied adhesive and the active centers which are introduced enable its more optimal chemical bonding.