Copper firing schedule

As you can tell by my latest posts, I've been dabbling in copper clay; specifically Hadar's powdered clays.  Several years ago I took a copper clay class from Debra Weld.  In that class we worked with CopperClay which is in lump form.  It was the very first copper clay to be introduced to the metal clay world.

True to my usual self, I had several pieces laying around from that class that had not yet been fired.  (Didn't have to worry about whether they were dry enough or not.)  According to Hadar, her firing schedule would work on all the clays, so I thought I'd give it a try.  It certainly does work.

This piece also was textured with a tear away texture that Debra had available in class.

Hadar suggests firing the clay in a two-step process.  The first firing burns off the binder and the second firing sinters the metal molecules.   First firing is 1100 degrees for a time of 30 minutes to two hours; depending on the size of the pieces and the amount of binder to be burned off.  The second firing is 1650 degrees for two hours.  (That's the schedule for copper.  If using copper and bronze together the second firing is 1520 degrees for two hours.)   

Firing is done in an oxygen free environment.  This is accomplished by firing in an open container that contains powdered charcoal.  (All charcoal is not created equal, so I used Hadar's to be sure.)  There's a half inch of charcoal underneath the pieces and an inch above the pieces.  Since I have a muffle kiln, I have to position my pieces towards the back of my container.  (The area by the door is cooler.)  After the first firing has cooled down, the thin layer of burned charcoal is blown off the top.  Then more charcoal is added to to the container to make sure there is enough on the top before starting the second firing.  

In the past I've had some copper firings that did not turn out.  (The water in the tumbler turned a pretty metallic color as the pieces disintegrated.)  So far this method has been the most successful for me.