9 hours ago, paulraphael said:Briquettes contain more incombustible minerals and thus leave behind a lot of ash.
What does a "lot" mean here? It may be true that lump leaves less ash than briquettel, but burn 5kg of briquettes, and you get comparatively very little weight of ash left behind. I think NM may be confused by the fluffy consistency of undisturbed briquette ash.