Jim Gremel Ceramics - Reduction Firing
Artist Jim Gremel checks the progress of a luster glaze Reduction Firing.
The huge flame shows there is not enough oxygen in the kiln to burn all the fuel inside. Hungry for oxygen, the hot gasses strip it from the clay and glaze reducing some glaze ingredients to pure metal (hence the term reduction firing).
Creating luster is a very tricky process. If the clay and glaze chemistry and the firing process are just right, the reduction will yield a beautiful metallic surface.