Kazegama

Steve Davis, Jamie Boran, Jonathan Cross, & Kaz Ota firing the Firebox Kiln

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By Hideo Mabuchi / Stanford University

Today I learned how to use a new analytic instrument that we have in the Nano Shared Facilities at Stanford:  something called a Thermal Gravimetric Analyzer (TGA).  This is basically a super-sensitive scale that can hold a sample of material inside a small electric oven, and that records changes in the weight of the sample as you ramp up the temperature.  As a quick test, I and my trainer set up a measurement with a tiny sample of stoneware clay and recorded the weight changes from room temperature up to 1000C.  That corresponds to about 1832F, which is a standard sort of bisque temperature, although we were increasing the temperature at quite a high rate, so I’m not sure it makes sense to associate this with any particular cone. Continue reading →

By Hideo Mabuchi / Stanford University

One of the neatest features of a Kazegama firing is the opportunity to observe the magic effects of Steve’s “sintered ash” on pot surfaces.  The sintered ash is obtained by sieving the largest chunks from a batch of wood ash, and a pile of sintered ash can be used as a refractory bedding under a pot, in place of the usual wadding.  Generally the part of the pot that has lain in/near the sintered ash picks striking up blue and even lavender colorations; this can be especially nice for side-fired tall forms like vases, bottles or pitchers. (To see more, go to Firing the Kazegama and scroll down to the “Sintered Ash” paragraph). Continue reading →