How It's Done

 

Working with crystals gives any potter a chance to push the envelope of his or her artistic and technical imagaination. If you are looking for a teacher, look no further than the challenge offered by the combination of porcelain and crystal glazes, especially when fired in a gas kiln.

The principles of patience, humility, compassion, and perseverance will be constant companions on your path.

If you are not a potter, celebrate any pot you like especially if it has crystal glazes, as it speaks of a potter who was willing to endure the maddening disappointments of endless firings that produced dreck.

The color on the pot on the right comes from cobalt.

Crystal glaze recipies appear stunningly simple. The glazes used for the pottery that brought you to this web site are composed of 3 basic ingredients (a frit, zinc oxide and silica) with a smattering of supporting agents (titanium dioxide, lithium carbonate, bentonite). Check out the key books currently available (see below) and you'll see plenty of recipies with little variation among them. Insignificant as those varitions might appear, they have profound effects on the success of the effort. The base glaze is not the whole glaze story--the coloring oxides used will have a profound effect not only on the color, but on the qualities of the firing. Some colorants will not work at the same temperature range as others.

Yet it is not just the recipie that is the key to crystal glaze success. The firing profile is critical. Yet so is the thickness of glaze application, the angle of the glaze on the ware, the type of clay, the temperature at which the green clay was bisqued, the atmosphere inside the kiln, the top temperature of the firing, and the soak temperature and time.

The crystals on the left are from nickle oxide.

If you are a potter looking for a quick road to crystal success, you will likely frustrate yourself. Embrace the slow, persistent, scientific and artistic path, work both sides of your brain to their maximum, and quietly smile when intuitive hunches move you into the crystal kingdom. Be respectful when you are there; arrogance may quickly lead to a kiln full of disappointment and landfill fodder. Precision tools help enormously in tracking this elusive royalty.

Pots thrown here are thrown using Aardvark Coleman porcelain available through the Clay Art Center in Tacoma WA. Porcelain is more expensive than any other clay body--some are several times the price of standard stoneware clay--another reason why crystal pots are more expensive than regular pots.

The ware is fired in a Skutt 12-27 electric kiln for bisquing. This kiln, like most today, has the essential feature of a programmable computer to manage the firing. Glazes are applied and the pots are fired in a fully computerized Geil 27 cubic foot propane downdraft fibre shuttle kiln. The gas kiln allows me to fire either more traditional cone 10 reduction glazes (the copper reds from this kiln are awesome and child's play to reproduce) or the much more complicated fully oxidation cone 10/11 crystal glazes shown here. Gas kilns are unheard of as a means of firing crystals. However, the crystals that emerge from a gas kiln are brighter, cleaner, and sharper than those from most electric kilns.

The pot on the right derives its color from copper.

The macro crystal glazes are derived from Fara Shimbo's "Crystal Glazes" book. Diane Creber has written a short, concise, and rich "Crystalline Glazes" book. No one should miss Peter Ilsley's book "Macro-Crystalline Glazes : The Challenge of Crystals". Jon and Leroy Price have written a book (published 2003) entitled "The Art of Crystalline Glazing" (Krause Publications).

Many web sites contain information on crystal potters and pottery. Enter "crystal glazes" in Google. One place to start is the Vicki Hardin site.

Art and science walk hand in hand to create beauty, simplicity, elegance and silence. 

 

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