Abstract: Provided is a method for internally coating the pores of a porous functional coating made of a base material with a hardening material that reduces the diffusion of the base material and/or the reactivity of the base material with the environment thereof. The hardening material is deposited from the gas phase onto the interior surfaces of the pores. It was recognized that by depositing hardening material from the gas phase, it can be introduced much deeper into the pore system of the functional coating than had been possible according to the prior art. This applies in particular when the hardening material is not itself introduced into the pore s stem, but rather one or two precursors thereof, and from said precursors the actual hardening material forms at the internal surfaces of the pores.