Method of manufacturing conductive film holes

1. A method for applying a coating to a substrate having a plurality of holes, the method comprising:

applying a braze material to a substrate having a plurality of holes, the braze material being an Au—Cu braze material unreactive to the substrate and the braze material comprising a braze paste, the braze paste comprising a water-based gel binder;

heating the substrate to melt the braze material to form a melt;

cooling the substrate to solidify the melt to form plugs in the respective holes;

applying a coating to the substrate; and

further heating the substrate to melt the plugs.

2. The method of claim 1 wherein:

the braze paste comprises particles of an alloy having a by weight composition of Au, Cu, and no more than 5% all other elements total, if any.

3. The method of claim 2 wherein:

a ratio of Au to Cu in said alloy is between 67/33 and 56/44.

4. The method of claim 2 wherein:

said particles of said alloy form at least 95% of alloy in the braze paste.

5. The method of claim 1 wherein:

said water-based gel binder forms 8% to 25% by weight of the braze paste.

6. The method of claim 1 further comprising:

machining the holes.

7. The method of claim 1 further comprising:

using pressurized gas to evacuate molten material of the plugs.

8. The method of claim 1 further comprising:

vibrating to evacuate molten material of the plugs.

9. The method of claim 1 wherein:

the coating comprises a ceramic layer.

10. The method of claim 1 wherein:

the substrate is a nickel-based superalloy.

11. The method of claim 1 wherein:

the substrate is a combustor panel substrate having a body formed as a frustoconical segment.

12. The method of claim 11 wherein:

the holes are along the body.