A comparison of proper softwood blacksmithing / bladesmithing charcoal with “overcooked” high temperature charcoal which is best suited for biochar applications.
Bladesmithing charcoal tests:
1. hard and clean, not crumbly and dusty
2. dense and solid, not spongy and blown out
3. musical and ringing when tapped, not dead and dull
4. burns with a blue and bright yellow flame, not a small dim orange flame
This video clip illustrates some of the physical differences between good blacksmithing charcoal and overcooked biochar charcoal: