CRYSTALLINE GLAZE & PORCELAIN POTTERY RESOURCE


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The Crystal Method

An interview with William Melstrom by Michael Barnes, Austin American-Statesman Arts Editor
Reprinted from the Austin American-Statesman, October 12, 2000

AA-S: How do you achieve the beautiful effects on your crystalline-glazed porcelain?
William Melstrom: I am actually growing crystals of glaze on the surface of my porcelain pieces. The growth occurs in my kiln at white-hot temperatures, while the glaze is a molten liquid, over a period of several hours. A nucleus forms on the glazed surface, around which "free-swimming" atoms of glaze attach in a regular lattice or chain-like structure. Atoms keep chaining onto each other, causing the crystal to slowly expand outward from the nucleus.
Snowflakes, which are ice crystals, occur in the same way, albeit at a much lower temperature. The nucleus of a snowflake is typically a speck of dust, upon which single molecules of water attach and freeze in regular patterns. The beautiful feathery patterns of frost on a windowpane are another example of ice crystals. The glaze crystals that I produce are often strikingly similar in appearance to Jack Frost and snowflakes.
Seven hours of growth results in a glaze crystal about three inches in diameter. A very exact temperature must "be maintained in my kiln during this time. Too hot, and the crystal will dissolve back into individual atoms of glaze. Too cool, and the glaze will stiffen and freeze, halting growth.
I cannot see what is happening in my closed, 2,000-degree kiln. I do not sprinkle anything on my pieces or "seed" the crystal nuclei. It is only through faith and experienced ? lots of both ? that I am able to achieve repeatable, acceptable work.

How does this differ from standard porcelain-making patterns?
There is nothing comparable to crystalline-glazes within the ceramics realm. It is generally regarded as the hardest glaze effect to achieve, which is why you so rarely see examples of it. It should be noted however, that the Chinese were accidentally growing crystals centuries ago, as their large, wood-fired kilns slowly cooled over periods of several days. The very small and misshapen crystals that resulted were a mystery to them and were regarded as uncontrollable defects.
The first examples of crystalline-glazed porcelain that bear any resemblance to present-day creations date to about 1900. Nowadays, the advent of computer-controlled kilns, which can precisely hold crystal-growing temperatures indefinitely, has greatly simplified the process. I use two programmable, electric kilns in my studio/home, and can be sleeping while they fire.

Are your porcelains primarily decorative or utilitarian?
My work is fully functional. It will stand up to dishwashers, microwaves and steak knives. You can stub out cigarettes on my surfaces ? my small trays make excellent ashtrays, which is fine with me. I really encourage people to get enjoyment from my pieces by using them daily in any way that they seem fit.
Of course, 50 percent of my customers just roll their eyes at me when I suggest this, telling me that they wouldn?t dream of using their pieces for other that decoration.
I put a gold rim on about half of my work. Gold in liquid form is brushed onto finished, fired pieces. These pieces are then returned to the kiln for a second, low-temperature firing, which bonds the gold to the glaze surface. As with any gold-decorated porcelain, my gold-rimmed plates cannot be microwaved.

Can you achieve other effects with your glazing process?
My glaze crystals grow within about a 50-degree temperature window. At the lower end of this range, perfectly round crystals ? often resembling sand dollars ? are produced. At the upper end, I get starbursts or "dandelion heads." In between, I get axe-head and German cross shapes. If I start at the high end of the window, and then go down to the low end and back up again, I get "halos" or "growth rings." These are similar to tree rings, and can be quite remarkable.
Each time I venture to the low end of the temperature window, it generates new crystal-forming nuclei, resulting in families of small crystals on the finished piece. My best work incorporates all of my effects: big and little crystals, halos, a variety of shapes, and just the right ratio of foreground space and background, or negative space.
Technically, the crystals formed are "zinc-silicate" crystals. Silica is the main ingredient of all glazes and glasses (and of quartz crystals), and zinc is another main ingredient of my glazes. Often, I produce secondary crystals of titanium, which appear as tiny golden flecks. Very rarely, I get a third type of crystals, which resemble tiny, ghostly stars, and which are a complete mystery to me.

How can the public see or purchase your porcelain?
My work is in several fine craft galleries throughout the country. I consider my "flagship" galleries to be the Hanson Galleries in Houston, Texas, 713-552-0007.