Posted 27 July 2010 - 07:27 AM
In the long ago days before the Internet, I was wondering about the use of charcoal. I found one book that had a diagram of the collier's mound-of-wood method of charcoal making: "Frontier Iron." I had a smithing class in the 1970's where one student was majoring in "Early Technology." This gent urged the others to approach me about making charcoal. We did have some billets of wood split and not over 18" long. We attempted to follow the book's methods with a couple of exceptions. Our mound was small by comparison, and we used softer woods because we were in New Mexico. We also covered our mound with adobe, because we had no damp humus in New Mexico.
We temporarily planted a 8"D x 9' pole vertically and began to stack the billets around it, sunburst pattern. As we proceeded, the stack began to take the appearance of a mound. We backed up the ole pickup and standing on the tailgate, wiggled the post out, leaving a cavity for fire building. We had made about eight 4"D portholes around the circumference a foot above the ground. The holes could be stuffed closed on the windward side if the charring process got too hot. We lit the fire with newspaper and kindling dropped down the central hole. Once the central fire was going, we stopped down the top hole about 90%. We allowed the porthole/tuyeres to do their job.
Two of my students volunteered to camp overnight in their sleeping bags in order to keep an eye of the mound. We did have a little collapse on one side, which they repaired with more adobe. A wind came up, so they plugged the tuyeres on that side.
About 10:00AM the next morning, we broke open the mound to find that we had about an 80% success rate. We found that soft wood charcoal works well in the forge, although one might not get as large a yield as using hard wood. Also, when forging, soft wood may give off a few more "fleas" (flying bits of hot ash) than hard wood.
In 2004, I gave a workshop in Costa Rica, and we used charcoal made by a professional collier (carbonero), simply because they have no mineral coal down there. That charcoal gave off quite a few fleas, so we wore long sleeved, cotton shirts.
When I gave a workshop in Australia near Brisbane, my host, Alan Ball, had a steel chest with hinged lid, about 3' x 3' x 4'. He started a fire in the bottom of the chest in the evening and after it was going pretty well, added a bunch of Eucalyptus logs and closed the lid. The next morning, we had charcoal.