‘Black Firing’, A Great Surprise

Anil is a large-hearted man, so as soon as he realised our curiosity and drive to learn all things pottery related he offered that we conduct our own “black firing” under his instruction. Anil has a small self-made raku type kiln. It is rectangular with an open top, has a grill between the firebox and “chamber” and has four fire mouths on all sides of its base. He advised us, while we worked, that if we were going to build ourselves our own kiln two mouths would be more than sufficient.

We didn’t have any of our own work bisque fired and therefore used objects from the pottery shop to conduct the experiment. First we gathered bits of scrap wood and a bag full of wood shavings from outside the carpentry. We then carefully loaded the kiln with the selected objects and began to generously cover the objects in sawdust and wood shavings and used even a few fresh leaves. Once the objects were concealed, we covered the top of the kiln with a metal sheet and placed bricks on the edges to hold it down. We were ready to begin firing.

We fired the kiln for three hours: a dreadfully smoky period where we constantly had to step aside to catch our breath or wipe tears away from our watering eyes. We kept the fire burning at a steady constant on all four sides and when the three hours were up we stopped feeding the fire. A paste made of mud and sand was used to seal the kiln and make it airtight. We began on top, carefully sealing the edges around the metal sheet and kiln wall. Then we sealed the mouths with bricks and pasted the edges with the wet sandy mud mixture. We continued in this manner, applying this paste, to any part of the kiln from where we saw smoke escaping, until it was completely airtight. The kiln was ready for its overnight haul.

Anil instructed us to open the kiln the following day after approximately 18 hours or when the kiln was cool enough. However, the following morning Mini accidently removed the bricks that sealed the four mouths, allowing fresh oxygen into the kiln. Luckily we took notice of this soon after and proceeded to emergency evacuate the fired ware from the kiln. The objects were still too hot to touch and so we used sticks and cloth, whatever we could find that worked, and pulled our treasures out. We were pretty thrilled.

Our curiosity is now awakened. We know now how to build our own kiln, and we know we can experiment ourselves. We have many questions regarding this process we want answered.

What happens if the time parameter of firing in reduction and/or oxidation is changed?
What happens if the temperature parameter is changed?
What happens if different materials are used during firing?
What causes the white marks?
What causes the matte effect?
What causes the metallic effect?
There is so much more to discover and learn.

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