They're glowing hot!
The use of a reduction chamber at the end of the raku firing was introduced by the American potter Paul Soldner in the 1960s to compensate for the difference in atmosphere between wood-fired Japanese raku kilns and gas-fired American kilns. Typically, pieces removed from the hot kiln are placed in masses of combustible material (e.g., straw, sawdust, or newspaper) to provide a reducing atmosphere for the glaze and to stain the exposed body surface with carbon.
Western raku potters rarely use lead as a glaze ingredient, due to its serious level of toxicity. Japanese potters substitute a non-lead frit. Although almost any low-fire glaze can be used, potters often use specially formulated glaze recipes that "crackle" or craze (present a cracked appearance), because the crazing lines take on a dark color from the carbon.
I was not incredibly impressed with our raku results. This is the technique that did produce the Ugly Pot, after all. Also, raku pots can't be used for kitchen or dining room use and can't hold water. They're for decorative purposes only. No good for sure.
