The ash-glaze tea bowl came out of a reduction firing that I almost called off.
The recipe, roughly:
- 40% wood ash (washed twice)
- 30% feldspar
- 30% silica
The magic is in the wash. Unwashed ash is too caustic and eats detail.
I write these up partly so I remember, and partly because the photos of each test are registered — the kiln log and the picture stay tied together.