Through the kiln door, between raw pots so fragile and hot
As to be luminous, Michael launches slim lengths of barkwood
Skinned by sawmill blades from new boards.
The lengths of wood he threads
From right and left, right and left, until nothing’s left
Of the pile that leaned against the brick hill.
It ignites like paper, like tissue. I fear for his eyelashes,
For the clay he has spent weeks giving shape.
The temperature drops as the kiln breathes to feed.
All around us, trees breathe in our exhaled breath
And sigh out oxygen to feed the fire and our lungs.
Late afternoon sun slabs down the mountainside
Like glaciers. Liquid ash and clay
Glow inside the cave. But what I meant to say,
I remember now, is salamanders.
I saw salamanders in the ash, glowing and whipping away
In search of the hottest parts.
They would not stay there just because I wanted them,
But between the shafts of oak and radiant clay,
They slipped at will.
I fire the kiln relatively quickly; between 42 and 48 hours. It must be attended during this time for twenty-four hours a day.
The stoking (putting wood in the kiln) starts slowly with a small campfire. This removes any remaining moisture from the pots, dries the kiln and starts to warm the bricks and the kiln itself. Over the course of the first day, the temperature is slowly increased with special care taken around 1060 F (571 C). At 1000 F, the quartz which naturally occurs in the clay, changes its dynamic molecular form, passing from an alpha to a beta molecular structure. If this change occurs too quickly or too erratically, the pots will crack. Once the temperature reaches about 2300 F (1260 C), the firing is slowed. At this temperature, the glazes have started to mature and becomes "sticky" enhancing their ability to capture ash as it moves through the kiln. The ash from the wood, since it contains fluxes (the growth salts of potassium, sodium, calcium and magnesium) along with silica, forms a glaze by itself at 2300 F. However, when combined with the applied glazes, it changes them to create a new chemical composition, i.e. changing a black-brown glaze to golden yellow. The kiln is maintained between 2300 F and 2400 F for a minimum of 8 hours but usually between 12 and 24 hours. This extended time at high temperature gives the materials within the glaze a chance to truly melt and since I fire with hardwood, it give the ash time to melt and incorporate itself into the molten glazes.
At the end of the firing, I crash cool the kiln for about one hour. Crash cooling brightens the glazes and minimizes the growth of crystals in the cooling glazes.