Last week we had a pit fire out in a field. There was a primitive kiln made of bricks, out in the open. I made some vessels on the wheel a year ago. The vessels for the pit fire need to be with 0.5 mm grogs, which is bigger than normal (0.2 mm). The grogs are tiny grains of fired and ground clay, which are added to the fresh clay. They give the unfired (or semi-fired) clay more structure and stability. You use this clay because the pit fire doesn't reach such high temperatures, and you're basically piling up the vessels one on top of the other among newspapers, branches, and leaves, and you want them to survive and be sturdy enough during and after a low temperature firing. This is the clay we usually use for making stuff by hand (not on the potter's wheel). Of course we had a bisque firing first - which is I think at around 800-900 degrees Celsius, so that the vessels won't break on the way. If you don't fire the vessel at all, then it'll become bone dry and be as brittle as a slab of chocolate.
Working with clay that has 0.5 mm grogs on the potters wheel is a challenge if you are new to it. The grogs on the fast-spinning clay are like sandpaper on your hands. You need to use a lot more water than usual, or use a slip (diluted clay that doesn't have grogs), to lubricate your hands and reduce friction. You also need to not press so hard and to minimize the duration of time when your hands are on the vessel. It's just a matter of practice and being familiar with it, understanding the clay and understanding yourself and what you're doing.
So at the time, which is a year ago, I was only experienced enough to make these small ones - they are about 10 cms high.
You can see a bluish tint on some of them - that would be the copper solution that we soaked the vessels in for a bit before firing them in the pit fire.
These two vessels below were fired at a high temperature (1100 C) which is not normally done for something that is headed for the pit fire. But they were made using clay with 0.5 grogs and I was OK with sending them off to the pit fire and seeing what would happen. The smoke did catch on OK, I think. I like how the glaze which was poured on selectively acts like a mask for the stains.
I used masks on the next two vessels. I placed an old doily lace cloth on the vessel and brushed on a slip, then took off the cloth. This created a nice mask effect. Next time I want to experiment more with masks. That, and buffing the vessels to get a dull shine and a smoother surface.
This one has a low-temperature glaze inside. It's interesting to see how the smoke penetrated the cracks in the glaze in some places.
The drips on this one are slip that was cast on before the fire. In this case the slip got burnt onto the pot, leaving its mark and a dark stain.
In other cases such as this one, the slip cleans right off after the pit fire, leaving a clean (whitish) area on the vessel.
And now for some non-pit fire work. My creations, ornamented with ideas from computer programming. The full album is up here on my picasa page.
I would love to hear your comments.
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