Charred Bones: Charcoal Making for Blacksmithing

At the Silvaticus Blades smithy, we use charcoal as our fuel for forging our knives and various other implements.  Burning hot and clean, it is a wonderful forging fuel, though not as long lived as coal.  However, having access to space and plentiful wood, making our charcoal is practical for us and thus using charcoal for our bladesmithing is our best option.

Charcoal, in this case, is wood burned in the absence of oxygen, leaving behind the carbon.  All impurities and moisture is burned off during the manufacture of the charcoal, leaving a clean and almost smokeless fuel.  Both softwoods and hardwoods may be used, and each variety of tree provides it's own special qualities to the charcoal.  Pine, for instance, burns very hot but very quickly.  More than likely, you will be using whatever wood you have available in your area.  I use oak because it is plentiful and burns long and hot.

I use an indirect method to produce my charcoal.  This means the wood to be turned to charcoal is placed in a sealed metal container (with a smoke vent) and is heated externally by a fire.  Oxygen can not enter the container so all of it's contents become charcoal.  Another way is the direct method, where your wood is stacked in a retort and allowed to smolder within, having the oxygen controlled by vents.  Eventually the retort is closed up and the fire allowed to die out.  Both methods consume wood to create the heat needed.  In the direct method, a portion of the wood within burns away, leaving behind ash.  In the indirect method, the wood outside the container, in the fire, is consumed. 

I prefer the indirect method because the wood I use for the fire can be trash wood, unsuitable for charcoal.  Brush, half rotten wood, stumps, whatever you have that will burn will work.  The direct method uses charcoal grade wood to produce the heat, thus wasting a high quality material when waste wood could be used.  Also, the indirect method is much less finicky, the sealed container regulates the oxygen, making the method pretty hands off as far as tending the fire goes.

Above is my metal container for holding the wood.  It is a 30 gallon trash can with holes poked in the lid to vent smoke.  As the wood turns to charcoal, it off gases impurities and steam in the form of smoke, creating pressure within the container.  You must have vent holes to relieve this pressure.  I wire the lid in place to make sure it does not fall off during the burn, which would introduce oxygen and burn up all the wood into ash.  These trash cans are galvanized, so do not stand downwind your first burn.  The metals used to galvanize the steel burn off and are toxic.

Here is the oak that I intend to turn to charcoal.  I try to pack it in as efficiently as possible, to maximize the end product.  I use stuff no bigger than a couple of inches across.

Here is my pit that will contain the fire.  I like using a pit because it reflects the heat back at the container, maximizing your fuel and allowing you to use less of it.  Some people will use a 55 gallon drum as their "pit".

Both ends of the pit have air vents to allow the fire to breathe.

Here, I have the container within the pit.  It is surrounded by fuel wood, which in this case is punky/termite ridden pine.  The fire has been lit.

A view of the fire from the air vent.

Once the fire is really raging, as in the above photo, I cover up the pit with a few pieces of corrugated metal, to reflect the heat down toward the container.

Here is the pit, covered.  As the fire burns, you'll notice smoke issuing from the vent holes in the lid of the metal container.  Eventually this smokes ignites and becomes a jet of flame.  You will know when your charcoal is done when there is no longer any smoke coming from the vent hole.  Allow the container to cool completely before opening.  If you open the container prematurely, the charcoal within will ignite and burn up.

Here is some finished charcoal, ready for the forge.  It will go on to forge knives, axes, and other edged tools.  It is even possible to get the charcoal fire hot enough to forge weld, however it uses quite a bit of fuel.  I love the smell and look of charcoal and it's clean burning qualities that make welding easier and does not impart impurities into my blades.  The ability to produce it here on the property is another plus and is easy when using the indirect method to do so.  I will continue to use charcoal in much of my forging, just like my ancestors in Rome did to forge their weapons and tools of antiquity.