No, this is not a new element. Rather, I was thinking, wouldn't it be nice if there was a graphics effect on wood where areas that are very hot would darken and turn dark grey with heat? I thought of this when I was burning away a wooden object, and found it slightly odd that wood didn't show any effect to the heat until the fire destroyed it. I was thinking that it could be the same type of effect seen when metals heat up and glow, only this would darken to a dark grey almost like coal in appearance.
I like it, it would be another interesting feature that's subtle, but, like boxmein said, interesting...
Thanks for the feedback. There is one extra detail I forgot to mention: If you dump water on burning wood to cool it off, the blackened areas remain blackened - they don't return to their original color.
I also find it a bit annoying when I have very hot wood in an airtight container, so that wood isn't touching any empty space or gas, but it still ignites. What if in that circumstance (hot wood completely surrounded by nonflammable element) the wood simply blackens instead. If temperatures exceed 1200°C with no contact to air, the blackened wood slowly converts to BCOL.
You got it exactly with that picture.