A method for coating a surface of a closed cooling channel, having a plurality of oil supply bores and a plurality of oil discharge bores, of a piston for an internal combustion engine, having a coating medium containing hexagonal boron nitride, comprising:
- a) introducing a defined quantity of the coating medium comprising a suspension of hexagonal boron nitride with a solution on a basis of at least one thermally curable inorganic binder and at least one solvent into the cooling channel;
- b) spreading the coating medium over the surface of the cooling channel by moving the piston about at least two spatial axes;
- c) using a laminar air flow to dry the coating medium spread over the surface of the cooling channel;
- and
- d) thermally curing the coating medium to complete a coating adhering to the surface of the cooling channel.