Finishing

Below are several finishing methods for PMC®.

Soldering, Tumbling, Sandblasting, Burnishing, Wire-Brushing, Enameling, Polishing, Pickling, Plating, applying Patina; or As-Fired.

Soldering

Although metallurgically just like other metals, PMC is structurally a little more porous than other metals. It can be joined by using the same flux, solder and torches as silver and gold, but because of its porosity, PMC will "soak up" solder. We recommend that you use hard solder, and when possible, prepare the areas to be soldered by burnishing to close the pores and reduce the tendency to absorb solder. It's important to use a delicate hand with the torch, removing the heat as soon as solder starts to flow. Even among conventional metals, fine silver and gold behave a little differently than their familiar alloys, so care and attention is recommended when soldering Precious Metal Clay.

Because of its porosity, PMC objects can retain pickle unless they are thoroughly rinsed. Neutralize the acid by boiling the pieces in a dilute solution of baking soda and water or by cleaning them in an ultrasonic machine for about 15 minutes.

Perhaps the most obvious option for finishing is to leave the PMC with the finish achieved in the kiln. In a piece that will be rubbed during wear, such as a ring, the raised areas will be burnished naturally while the recesses remain white (silver) or yellow (gold). To polish to a high shine, the metal should be burnished, either by hand or by mechanical polishing. Magnetic polishers, in which small rods and spheres of steel are tossed against the work by rotating magnets are ideal because of their speed and ability to polish without damaging the surface.

To burnish by hand, use a steel burnisher to rub the surface smooth. Follow with a light treatment of polishing compound (such as white diamond or Tripoli). After washing with soap and water, the final polish is achieved with rouge applied by conventional wheels and polishing machines.

Silver PMC can be oxidized with liver of sulfur or a proprietary colorant just like the conventional metals. Pure gold is very difficult to color in this or any other form and will require commercial solvents, paint or plating.