• K2

Earth + Fire

Updated: Aug 29

Ever wonder how the ceramic process works? I'm fascinated by it and I think you'll be too once you know more. Ceramics, like many other art processes, is a multi-staged process. Here is my quick-and-dirty explanation:

Some potters, like the artisans of yore, still dig up their own raw clay from deposits in the earth and make pots out of it. Clay is a naturally occurring substance in the ground and if you let it become bone dry, pulverize it, and slake it again (submerge it in water), you can pour the slurry through a mesh to filter out any debris or stones. The resulting slurry is then allowed to drain of excess water and slowly dry to a firm yet pliable state, after which this malleable material is wrapped in plastic for later use. Commercial clay suppliers do this hard and dirty work with machinery and heavy equipment but it's interesting to know there are potters still doing this hard and dirty step... There are online videos of potters demonstrating exactly how to do this.

A lump of soft clay is essential for "throwing" on a wheel-- anyone who's watched a skilled potter do this is mesmerized by the way the pot forms and grows as if by magic. Clay can also be rolled into slabs or coils, pinched into pots, constructed, sculpted, and extruded. Pottery was among the very first human arts/ technological developments and it is amazing to think that 35,000 or so years later, its forms and uses haven't as yet been exhausted.

When a piece of formed clay is bone dry, the unfired pieces are called "greenware" and they're also at their most fragile. When the ware is fired for the first time in a kiln, it's called "bisqueware". It is much less fragile, and more easily handled for processes like glazing or underglazing. Then the ware is fired a *second* time at a higher temperature with glazes that have been applied to the surfaces. The glaze "seals" the surface of the clay and makes the pots water-proof. Recently, divers in the Mediterranean found an ancient shipwreck which had hundreds of amphorae. The wooden ship was long gone but the clay vessels had survived on the sea floor~ intact!~ since the Greek Hellenic period, approximately 2000 years ago.

Glaze is more mysterious. It's likely that the ancient potters observed that some of their pots came out of the kiln with colored, glassy surfaces and theorized that the pots got that way from the wafting wood ash that landed on the ware during firing. A mixture of ash and water is one kind of very simple recipe for making glazes. Today's commercial glazes tend to be comprised of a feldspar, a flux, and silica and when oxides are added to the formula, the variations for colors and surface finish are endless.

I use the modern two-step firing method that was developed in the 1970s: my greenware is first fired to temps of 1800 deg F (Cone 04), and then the ware is glazed and fired to stoneware temps of about 2200 deg F (Cone 6).

Here are some of my goofypots coming out of a bisque-firing.

If you enjoyed this post, let me know in the comments!


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