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As we’ve noted with the release of several previous videos, the Primitive Technology YouTube channel seems to be gradually headed towards the age of metallurgy. This channel started out with simple videos on how to build tools and shelters in the Australian jungle, and has gradually evolved into more complex items. Most recently, he developed a sophisticated hydraulic hammer and several types of pottery kilns.
In his latest video, the silent host of this informative channel shows off an even more efficient and powerful source of heat: a draft furnace.
Two previous forge videos showed how to construct a rotary blower that forced air into a combustion chamber, cranking up the heat enough to smelt small iron particles from naturally-occurring ore. While effective, these blowers require constant effort — and that means burning valuable calories.
The advantage to a draft furnace is that there’s no continuous labor involved, aside from feeding the fire with charcoal or wood fuel. The channel host sculpted his furnace from clay in a large cylinder, leaving an air vent tube — known as a tuyere — in the side.
The tuyere allows the furnace to pull in air naturally, and brings the fuel to a white-hot glow. In the YouTube video description, the host goes into detail about the design and estimated temperature output (he claims 1200°C/2192°F).
The draft furnace was tested on chunks of impure bog ore found nearby; this new source melted and hardened but didn’t produce pure iron. However, by experimenting with iron bacteria in previous videos, he should be able to produce enough pure iron particles to start forging tools.
It’s one step closer to entering the iron age, and that’s pretty cool considering the host has used no modern tools or equipment to achieve this. He might be forging blades in no time.
Past videos showed how to make a forge with a manual blower.
The draft furnace was built from termite mound clay reinforced with plant fibers.
The furnace began as a small foundation, and grew upward to shoulder height.
Wood fuel and bog ore were inserted into the top of the furnace.