Betty,

 Assuming ceramic shell....or are you talking solid investment?  anyway, there is always the risk of nasty carbon left over in the molds.  I have burned out many things in my kiln.  Our kiln spikes early at 1900, then drops back to 1700 - wax is removed in 10 minutes, molds fire for an additional 40 to 50 minutes. Works great.  I will attempt at uploading a picture of the kiln I use.

George 

KeystoneArt.org

Betty,

I've cast all sorts of things, from spiders to a human pinky finger section. (The guy who lost it wanted a memento.) I just invest them the usual way Iwould for wax and then burn them out. I extend the burnout time a bit and sometimes blow a shot of oxygen from my O/A torch down the sprue hole a few minutes before casting, though that's really more of a superstition that a fact-based procedure. I generally took the burnout kiln up to about 1200F and held it for an hour pre inch of investment thickness and that always worked for me. The investment was Kerr SatinCast, if it matters.

Since the pinkie finger joint was just "un-tanned" leather, I woud certainly think you could do what you propose. Good luck!