About the Process
Crystalline glazing is a unique glazing technique in which crystals are grown on the surface of the pot during the firing process. Good crystalline glazing is a balancing act between glaze composition, firing schedule, glaze thickness, pot shape, and pedestal construction. When all of these factors are aligned, the crystalline glazes sing. But knock one factor out of alignment by only a small margin, and the results can be terrible: no crystals, ugly rough crystals, broken pieces, bizarre colors, or strange surface bumps.
To achieve the two-dimensional crystals you see on the surfaces of these pots, I mix several glaze ingredients together in very precise ratios. The two important ingredients are zinc oxide and silica; these two minerals combine during the firing to form zinc silicate crystals. Once the glaze has been mixed, I apply three thick coats to every piece using a large Japanese style paintbrush. Crystalline glazes are very runny when fired, so after the glazing process each piece is a glued to a pedestal designed to catch the runoff glaze. Next, I load the pieces into the kiln and fire them to approximately 2345 degrees Fahrenheit. A brief “hold” at this temperature is followed by a temperature drop to ~2000 degrees Fahrenheit. I hold the kiln at 2000 degrees for approximately 2 hours; this is the primary crystal growing period. A few more programmed temperature fluctuations, and the kiln shuts off.
After allowing the kiln to cool naturally, I unload the pieces and tap the pedestals firmly on the ground to separate them from the pots. Once the pieces have cooled completely, I grind the bases with a bench grinder and again with a rotating silicon carbide disc. Finally, the pieces are carefully washed and dried before being priced, photographed, or sold.