Wednesday, April 6, 2011

Planning the pit firing

Adorable hubby wants to cook a bunch of clay chunks and use it as grog in some of the soggy spots in our road, since we have lots of clay and lots of wood. I am escalating this plan to a regular pit firing of some pottery, which I will invite my pottery friends to, with the goal of getting some pieces that look like This!

Here is a nice link that gave me lots of ideas, and here is another one with great pictures.

Ceramics Monthly also posted this very concise summary of what to do:

1. Dig a pit of the appropriate size, depending on the amount of work to be fired.

2. Place a bed of dry leaves and twigs and possibly coal, which will burn slowly, at the bottom of the pit

3. Place the pottery on top of this.

4. Carefully sprinkle oxides and carbonates around the pieces (particularly copper carbonate), which volatilize and result in flashes of color appearing on the fired work.

5. Cover the work with more leaves, twigs and dung (if available), building up a mound over the pieces.

6. Once the stacking process is finished, light the pile around the edges and leave to smolder for several hours, or until the next day.

7. Towards the end of the burning process, bury the pit in earth or sand, which will cut off the oxygen supply and create a strong reducing atmosphere inside the mound.

8. Allow the kiln to cool overnight and open the next day.

9. Remove excess scum with a wire brush under a running tap.

Tips:

1. Additions of grog or volcanic ash 'open up' the clay and make it more resistant to heat shock.

2. The best color results can be achieved with iron bearing, or red clays.

3. Bisque firing the work first helps to prevent shattering and cracking.

Not hard at all! I've done this with just a few pots in a garbage can. Maybe I'll do a little experimental hole in the ground the first part of May, before I invite a bunch of people over for a party.

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