similar to the complaint about smokehouses (but not nearly as extreme), if you fuel a crucible with wood instead of coal, you can't use it for some recipes
so, in that case, let me extinguish the dang thing so that i can try again with only coal- or have it be considered to be coal-fueled if i then put in coal afterwards
also, tell me in the crafting recipe for each new thing what exactly needs coal and doesn't (i.e a crucible icon with a coal next to it in the tools: section)