IN TRANSITION FROM WOOD TO CHARCOAL

It will be well over 400 deg C inside the kiln (or so they tell me) and here's how it looked last night poking my camera close to the 'shoe', just after I had reversed the air flows (by moving each flue to the next shoe). 

The wood you can see glowing red here had been almost completely starved of oxygen moments earlier when it was the last thing the combustion gasses and SMOKE saw before dashing up the flue.  But now it's rich in oxygen supply because now fresh air is hitting it on the way in - it means what you are looking at is part-charred wood actually burning furiously.

It never fails to excite me to see this violent reaction being contained by a centuries old man-made process.