The new “OneFire Sterling PMC” is a fabulous new clay. OneFire Sterling PMC allows for a single step firing but with the added strength of sterling! Metal clay artist extraordinaire Celie Fago, who is one of the original Metal Clay aficionados' came up with the idea to combine metal clays into a single fire sterling 960 brilliant was an turning point for all metal clay artists. Mitsubishi Materials Trading Corp has now taken the clay one step further and it can be open shelf fired like the other brands of Silver Metal. So the great news is... there is no need for activated carbon in the firing process. Simply add pieces to a cold kiln, ramp at full speed to 871-898ºC and hold for one hour!