- The tools needed for this job are a hammer, a flat-headed punch or a hammer hand piece for your flex-shaft, a small round burr, and some platinum wire: You will also need either; dog-leg style burnisher or a tungsten burnisher made from a burr, as well as a wire curter and a pair of needle-nose pliers.
- A sheet of platinum with a porosity pit. For this demonstration, I’ve simulated the porosity by using a sharp punch on the metal.
- Using the round burr, reform the irregularly shaped cavity until it is exactly round.4. Turn the cavity into an oval by burring the inside of the hole at an angle. This will enable the platinum plug we will create to fit snugly inside the cavity.
- Melt the end of the platinum wire to form a ball that is the approximate diameter of the hole.6. Try to match the size of the ball to that of the burr you chose.7. Using the needle-nose pliers, grab the wire and push the ball into the cavity.
- The ball should pop in and fit tightly. (This will take a bit of practice.)
- Clip off the wire, leaving the ball inside the cavity and a small amount of wire-no more than 1 mm protruding from the hole.
- Using the flat-headed punch or the hammer hand piece, gently flatten the wire.
- This action will spread the ball inside the cavity and help blend the repair area with the rest of the surface.
- With a small needle file, remove any excess metal, then burnish the repair area. Burnishing the area will further compact the surface and help’ to eliminate any seams.
- Sand polish and finish as usual, using a series of platinum polishing compounds (800, 1500,4000, 8000). The advantage of repairing porosity mechanically is that it allows you to repair near stones without using a torch. This can also be done by lasers, but not all shops may have a laser at hand (or be able to afford one).
- The repair is virtually invisible.
AJM, May 2000
Jurgen J. Maerz
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