I always associated clinkers with actual coal stoves. I assumed they were non-combustible mineral components and aggregated at the bottom and had to periodically be disposed of.
But now I’ve found clinkers at the bottom of my grill in the remains of natural chunk charcoal. Apparently I need this whole process explained to me.
I have a wood cook stove in my hunting shack that is also used for overnight heat.
When burning coal or wood there will be small chunks that fall through the grates into the ash pan and when the pan is empty they clink when they fall.
Now that may not be everyone’s definition of a clinker but its mine.
I’m confused. The blacksmiths at the recreated 18th and 19th century “villages” always explained to me that they hated using coal rather than charcoal because mineral coal gave you clinkers that you had to scrape away. Natural charcoal, they explained, wouldn’t do that.
If you’re getting clinkers from bags of wood charcoal then it suggests that they’re adulterated somehow. But I have no idea how. Poor control of the stuff as it’s “charring”, so stones and pebbles get in? Storage contamination? Stuff getting in as it’s being crushed to size or molded into shape?
Charcoal is not pure carbon. Although most of the gaseous elements that comprise wood, mostly oxygen, hydrogen and nitrogen, will be driven off when wood is converted to charcoal, as will most of those elements that oxidize into a gaseous form (such as sulfur and phosphorus), there are other solid elements that are present in wood (in small quantities), such as calcium, potassium, sodium, magnesium, iron, silicon, and manganese, and which do not readily form gaseous compounds. These will be left behind in the charcoal, and will form ash or clinker when the carbon itself is burned off as CO2
I use the Royal Oak lump in the 20lb blue bags pretty much exclusively.
It is rare to get a bag that doesn’t have some chunks of brick, stone, concrete or similar debris.
IME briquettes of whatever provenance burn down to ash, but “lump charcoal” will contain some stone fragments. I don’t know why. The two brands I get a lot are Royal Oak and Cowboy.
Mystery possibly solved…I just dumped charcoal into the chimney, and out tumbled a fist-size lump of scorched earth. Smaller lumps I didn’t notice before would account for the clinkers.
And you’re welcome for reminding you about Scorched Earth.
Lump charcoal theoretically has very little mineral matter and forms virtually no clinkers. The mineral matter in lump charcoal is mostly alkali metals that do not form clinkers. That said, during/after the manufacture of lump charcoal (In ovens) external soil finds it’s way into the charcoal - hence the clinker.
Blacksmiths prefer anthracite coal ( the hardest and hottest burning). However, a lot of blacksmiths use lump charcoal these days due to easy availability and there is no sulfur/arsenic/other harmful stuff in lump charcoal.