Abstract: A method of coating a component (6) having at least one passage (16) entirely therethrough. The method comprising the steps of applying a coating (28) to a region of the surface (22) of the component (6), adjacent to one end of the passage. Then directing a liquid jet (38) through the other end of the said passage (16) so as to remove at least a portion of any coating material (28) located within, or obstructing, the passage (16). In this method the jet is channelled by a first portion (42) of the passage (16) before it encounters the coating material (28) within, or obstructing, the passage (16). In particular the jet (38) is a water jet, which is used to remove a ceramic coating (28) from a component (6). The method has particular use in clearing cooling holes (16) within combustor components or turbine blades. The method can also be used in the repair of such components (6).