In a woodfire, fine particle of ash fly through the kiln.
These particles adhere to the pots.
At high temperature the ash particles melt and glassify.
Close to the firebox the result can be thick, ropey rivulets of ash accumulation.
On the floor by the firebox, a crusty, charcaol surface might form.
Farther back in the kiln, the result might be a more subtle speckling.
Vaporized salts from the wood bark can cause flashes of atmospheric color and a glossy sheen.
When these elemental yunomis went in the the anagama they were raw, pure-white porcelain. They were near the mid-point of the kiln. All of the speckling, all blushes of color came from the woodfire atmosphere.
If the rivulets of melting ash run down a pot onto a kiln shelf, the pot may be permanently adhered to the shelf. To avoid this, each pot is placed on pieces of wadding - a punky clay that becomes brittle when fired and can be broken away. Any spot that is wadded is also shielded from the woodfire atmosphere, creating a halo where the wadding once was. These yunomis were fired in pairs stacked lip to lip. Wadding halos can be seen on all the lips and on two of the feet. The two feet with uninterrupted ash speckling were the tops of the stacks (with the feet facing up.)