[kragen]

ash has no carbon

carbon's oxides are all gaseous at standard temperature and pressure

[lliamander]

Not quite. Plenty of carbon is release as carbon oxides, but calcium carbonate is also a major component of ash (or at least wood ash).

[kragen]

good point

little carbon, then, not none

[elihu]

Going by what wikipedia says, wood ash can have carbon. If I understand correctly, how much depends largely on how hot it burned.

https://en.wikipedia.org/wiki/Wood_ash#Elemental_analysis