Forester, you have really done your homework!
My hypothesizing has been met by your scholarly findings.
Just to clear up where I was coming from. If you fire ceramics at 2300 degrees farenheit using a "groundhog" kiln, a very powerful draft is created, and the wood is virtually vaporized, and I suppose any remaining ash is carried out. (Some fly ash sticks to the pots). At the end of the process, when you look inside the kiln it looks clean of ash. (I suppose there may be small traces. And if you check the areas around kilns you no doubt find wood scraps and piles of unused fuel! Hard to believe the archeologists coulld actuly find residue of olive oil in the ovens!)
But you wouldn't find the thick layers of ash that the archaeologists found. So the Egyptians were clearly using a different process that did, indeed, leave ashes, and which I did not understand.
I was impressed to learn that they used blowing tubes!
But, going back to the groundhog kiln technology, the draft increases as
the temperature rises, and you don't need bellows or any forced air. THe heat draws the oxygen through the burning fuel. This technique might have lowered the death rate among assistant copper smelters!
However, there may be many reasons why it would not have worked.)
This is what I was thinking of before reading all your posts.

The deeper you go, the higher you fly.