A. Geez, I wish the answer had been as easy to write as the question. Have been around the world on this one, to little avail. The problem is that making pottery is very energy intensive. See our discussion of ceramic vs other drinking vessels. Looked for solar kilns and while there was some mention, here and there, I failed to elict any firm details. Generally it was felt to be lovely idea, but too hard for the average potter to generate sufficient sustained heat for firing, using the sun alone. Even the world acclaimed Richard Bresnahan, Artist-in-Residence at Saint John's University. Minnesota, USA, who lectures in "Art and Sustainability" doesn't use a solar kiln. Admittedly, his Johanna Kiln, is made from recycled bricks but to get it up to, and maintained at 2,850oF (1,566oC) requires...... a heap of wood waste. Though, on another tack, he uses a straw ash glaze. Dried navybean, sunflower, flax and soybean is turned to ash and mixed with water, refined clay and feldspar.
So what do you do, if you can't lower the temperature that clay is fired at, and all the inherent energy load that involves? You rethink the problem. And this is what the Tagawa Sangyo company of Japan did. They make ceramic tiles, without even firing them! Called Limix, the product is made by adding slaked lime as a binder. This apparently, reacts with carbon dioxide in the atmosphere and starts to harden. The application of a two tonne press certainly encourages the hardening, along with the chemical reaction, and a high density product is created. One that that continues to harden as it ages. It has the strength of cement and can be cut like porcelain. The tiles (shown above) won the Fukuoka Industrial Design Prize and are fully commerical at the cost of ¥ 9,800 - 18,000 per m2. Whether the technology can be applied to other ceramic based products was, alas, beyond my Japanese translation skills. But the company does have several patents to its name.
Also from Japan, is another solution to the low energy ceramics conundrum. Green Life 21 tableware is a collection of ceramic goods (such as the teapot with cups, shown above). Made from recycled post-consumer and post-industrial waste from clay-based crockery, in a process, that is said to not emit any more carbon dioxide, than conventional tableware manufacturing. Certainly the clay extraction process is fortunately forfeited for this second-time around pottery. Hard to tell if any 'down-cycling' is involved but plates made from plates sounds like a 'technical nutrient' to me. Mr McDonough would be proud.
Now, whether this is what you were after GH, I'm not sure, but hopefully it's a start, me old china plate.* Maybe our worldy readers have some other tips? [by WM]
* (Rhyming slang for 'mate'. Seemed appropriate for a post on ceramics)