One additional idea I might suggest is when cold flame, or anything extremely cold for that matter hits wood, would be for the wood to whiten to simulate moisture in it freezing. Also, I agree with MaksProg that fire is too cool in temperature.
plead-for-destruction:
useless....
...plus we already have coal and broken coal...
..plus when stress is added the remaining pieces will fall to the ground
We already have one *facepalm*
At this point I would tell you to just make another thread...
But what's the point of having a gas filter as a powder?
Listen, my burnt wood suggestion does NOT add any elements. Plus, we don't need an element called charcoal. In real life, charcoal burns slowly. In the Powder Toy, coal does the exact same thing. As for a gas filter, look in the walls category at that greenish wall. That only allows gasses through.