A major complication in firing crystalline
glazes, is that at their maximum temperatures,
during firing, they are very fluid. Atoms within the molten glaze have
to be able to freely move around and attach to each other in a tight pattern.
This pattern is called a crystal.This fluidity means that the glaze is going to run. On a vertical surface,
such as a vase, a crystalline glaze tends to flow right down the pot and
onto the kiln shelf, ruining both.There are a number of ways to deal with this problem.
Most are variations of the pedestal and catch basin technique. The vase
is placed on top of a thrown, porcelain ring, both of which are then placed
in a shallow dish. During firing, excess glaze flows off the pot, down
the pedestal ring, and right into the catch dish, where it collects. After the piece has cooled, the pedestal is broken off the vase, and the
sharp, glass-like glaze edge is ground smooth.
I use an entirely different method of controlling glaze flow. Over the years, I have developed the ability to exactly predict how much the glaze will flow, and a system for applying precisely the right amount of glaze to my pieces. I apply my glazes paper-thin to the bottoms of my pieces, and as much as an eighth of an inch thick at the top. During firing, my glazes flow down just enough to give me an even coat from top to bottom, stopping just before they reach the kiln shelf.
It isn't easy to do. I collect crystalline-glazed porcelain, and I've studied the work of dozens of crystal artists, but I know of nobody who uses my method.
Which system is better? Neither, really. However, I feel that there is something artificial about using pedestals and catch basins. It's as if the very nature of the glaze is being denied and hidden from the observer.
The bottoms of my pieces ideally end in a nice, fat, luscious, glaze roll. You can easily envision the actual glaze movement that took place in the kiln. I often get one or more glaze runs, which I also view as luscious and fascinating.
If my firing takes a bit too long, or if I apply a little too much glaze to a piece, the glaze sometimes does flow all the way down to the shelf. Sometimes it's okay, and I end up with tiny puddles that look just like wax that has run down a candle stick, onto a table. Sometimes, it's not okay, and the glaze gets under the piece, and has to be ground off.
Speaking of glaze flow: I usually apply a non-crystalline glaze to the rims or lips of my work. It is applied as a very thin band, right at the very top of my pieces. During firing, the rim glaze flows down the sides of my work along with the crystalline glaze. It is amazing how far these glazes travel, as much as six inches and more on my tallest vases and largest bowls. These signature glaze drips record what actually took place in the white-hot kiln as the piece was created.
