exploding charcoal
Refers to charcoal that pops or sparks when burning, often due to trapped moisture or air pockets. Compare with 跳ね炭, which also means popping charcoal.
See also: 跳ね炭
Be careful with exploding charcoal so that sparks don't fly.
Compound of 走り (hashiri, 'running') + 炭 (sumi, 'charcoal'), referring to charcoal that 'runs' or scatters sparks.