Crystalline Glaze
Crystalline glaze, the Chinese call it "firecracker glaze", can be traced back to the Chinese Song Dynasty (960-1279 AD). Although the technique is over a thousand years old, it wasn't until the late 19th century that the glaze was studied and commercially produced. The technique is rarely seen in commercial production today, and this elusive glaze remains a fascination of contemporary studio potters.
In most pottery work, a 5-10% loss can be expected during firing. With crystalline firings, 50% can be lost. It is a high fire proces, with an eight hour hod time at over 2000 degrees. During that time, if the kiln gods are with you, crystals will form. If the thickness of the glaze is not right, or the temperature is missed by as little as 25 degrees, the result is clear glass!
A number of different materials can be used to form crystals. I use zinc and fire on porcelain clay. Each vase is fired on a handmade pedestal, which is knocked off with a hammer and discarded after firing.
It is an exacting work to produce crystalline pieces consistently, but because of the singular beauty I find the challenge worth the effort.
-Dale Donovan
One of Dale's crystalline vases |
Another of Dale's crystalline vases |