The first step in making my work is to cut up the clay and weigh it so all the pieces of clay are the correct weight for the shape I’ll be making. I then wedge the clay to make it consistent and work out any air bubbles. Sometimes Lydia tries to help.
Most of my work is made on the potter’s wheel. First the ball of clay must be centered perfectly on the wheel, then I make a small opening in the middle of the clay, open it up, and start to pull the walls up.
Work is then allowed to dry completely before loading in the kiln for the first firing to over 1900F
Once they are bisqued, the pieces are sturdier and a bright terra cotta color. All water down to the molecular level is removed by this firing so these pieces can never be turned back into workable clay. Pieces have been dug up that are over 20,000 years old that have been fired to this temperature or less
After the pots have been bisque fired I dip them into my glaze and load them back into the kiln for the glaze firing, which goes to about 2200F
I cut my stencils out of Tyvek, which can hold up to multiple uses. I enjoy running, and I’ve found my old race bibs are a good source of Tyvek.
Some of the designs I work with are printed onto the surface of the clay. I create screens just like those that are used to print t-shirts.
Certain Laser printers have high iron content (a very common glaze ingredient) in their black ink. I create my decals in Photoshop, print them out, and apply them to the finished, glazed work, and then put them back in the kiln for a third firing. The decal burns away, but the iron in the ink sets into the glaze. Justin Rothshank has a great resource page for learning more about decals.
Glaze formulation is a very complex science that involves designing what is in your glaze down to the molecular level. Many good recipes are already out there, but I had to do a bunch of testing and redesigning of my glazes to get just the effects and colors I was looking for.
In woodfiring, wood is used as the heat source, and the kiln gets up to above 2400F. The wood also creates the glaze on the surface of the pots. Over the course of a tree's life, it sucks minerals up from the ground, many of them are the same minerals we use in glaze formulation. When we burn the wood in the kiln, the flame flows through the kiln and deposits ash on the pots. The ash contains these trace metals, and when the kiln gets hot enough, they melt, stick to the pottery, and form a glaze on the surface. The finished pieces show the path the flame took through the kiln.
Because the ash from the wood glazes everything in the kiln, the pots and shelves would stick together. We separate everything in the kiln from each other with wadding - a mix of clay, sawdust and sand - that resists the ash and can be easily knocked off the pots after the kiln is unloaded. We also sometimes use sea shells that leave a beautiful scalloped pattern on the pot.
Getting glaze to melt depends not just on temperature, but time. Holding for hours just under the temperature you want can cause glaze to melt. Because of this we don't really worry too much about the temperature in the kiln, but instead rely on pyrometric cones that melt the way glaze melts. We formulate our glazes to match specific cones.
The materials we use in glazes are natural minerals dug from the ground. Trees, over the course of their lives, soak up these minerals into themselves through the water. As we burn the wood, these trace metals float on the ash, hit the hot pots, stick to them, and melt - creating the glaze. The fire flows through the kiln like water, depositing ash on the pots as it goes, creating the marks and ash drips that are so distinctive to wood firing.
We climb into the kiln to load the pots - working our way forward, then bricking up the door.
We stack pots on top of each other, separating them with wadding. This saves space in the kiln, but also creates the opportunity for the fire to flash around the wadding.
Flame really does flow like water. As we load the kiln, we try to keep a good deal of space between the pots and visualize the path the flame will take through the kiln so we don't create cold spots.
After a few hours of warming up the kiln, the fire is sucked backwards through the kiln as the chimney starts to draw.
We leave a small hole in the door to stoke the wood into the kiln and cover it when we aren't stoking. Once the kiln is hot, the wood bursts into flame in our hands as we throw it into the kiln.
We stoke the kiln every 10-20 minutes around the clock. Firing times vary from kiln to kiln - some kilns fire off in 24 hours and some take weeks - but we generally light the kiln Friday evening and fire until Sunday afternoon. There is something special about spending the early hours of the day alone with a kiln, much the way potters have been doing it for thousands of years.
One of the things I love about woodfiring is the community aspect. You need a team to fire the kiln. I love bringing groups of students out to fire the kiln and fall in love with the process.
We normally use about 2 cords of wood per firing. That's a lot of splitting and stacking.