US Patent 7147899 Process of masking cooling holes of a gas turbine component

A process of masking cooling holes (4) of a gas turbine component (1) with an external surface (6), including a cavity (2) and a plurality of cooling holes (4) before coating the gas turbine component (1), includes first applying a mask material (5) to the cooling holes (4) so that the cooling holes are filled at least closest to the external surface (6), whereby the mask material (5) contains a filler material. Then the mask material (5) within the cooling holes (4) is thickening and the coating (8) is applied to the external surface (6) of the component (1) and the masked cooling holes (4). In the end remaining thickened mask material (5a) is removed from the cooling holes (4).