There are some important things going on in the coal forge when using it. Unfortunately I can not just throw steel in there and wait, as one does with a the gas forges. First off I use coal. Coal needs to “cook” and >transform into “coke.” The coke is the fuel in the fire. It is what makes the forge able to do what it does best, burn. A product of the process as well is klinker. It gathers at the bottom and can really create a messy fire if not taken care of. Klinker also with make a dirty fire and can add to the difficulty of forge welding. On three sides I have coal cooking into coke. The coke burning and in the center there is a void of intense, controlled heat in which I lay the iron.
I typically keep some kind of opening so I can see in there. Every time I pull the iron out I destroy the fire a little at a time, which in turn has me gather it up getting it ready for the next heat. Defiantly a relationship between the smith and the fire. Not to sound to corny but a relationship of creation, life and death of that tool.