How do you make charcoal?
Carefully?
Generally, I don't. However, charcoal is the result of incomplete combustion of wood or organic products.
A rather harrowing description of the process was made by Eric Sloane, who casually mentioned that a careless charcoal tender could fall into his makeshift oven and be completely consumed in minutes.
Those were crude affairs, with the wood dragged up into a pile and covered with dirt. A blaze was set, and the tender watched over it as if baking a cake for a week, adding more oxygen here, and covering the holes there, to assure proper cooking.
Hopefully, at the end of the process, a more or less pure carbon residue, with all the combustible gases and water driven off, would then be available to make iron with in the blacksmith's iron furnace.
It was an eminently wasteful procedure, of materials, labor, lungs and sometimes lives.
The amount of charcoal used to smelt iron was staggering, but the amount of wood used to make the charcoal was almost beyond comprehension. In 1840 the small town of Salisbury, Connecticut was using five thousand cords of wood a year in the manufacture of iron. This amount is hardly more than a mathematical figure, but if you visualize it in the form of one pile of wood in cord-width, (4' x 4'), such a woodpile would be over seven miles long. This, multiplied by the hundreds of iron-producing towns of that time, made a pitiful gap in the forests of America and cleared the farmer's countryside of every available tree. -- ("Eric Sloane's America")