Primitive Technology: Blower and charcoal

Primitive Technology
Published on May 18, 2018

I made a blower and some charcoal at the new area in order to create higher temperatures in for advancing my material technology. I took Fan palm leaves and fashioned them into an impellor (about 25 cm in diameter) held in a split stick as a rotor. I then built a housing from clay (slightly more than 25 cm diameter with inlet and outlet openings about 8cm in diameter) and assembled the blower. I opted not to make a bow or cord mechanism as I’ve done before due to the complexity and lower portability of such a device. The lighter impellor material (leaf instead of the previous bark) made it easier to spin by hand anyway as it has a lower momentum. Each stroke of the spindle with the hand produces 4 rotations, so about 2 strokes per second gives 480 rpm. The blower increases the heat of a fire when blowing into it and I would guess it’s more effective than a blow pipe and lungs but don’t know how it would compare to a primitive pot or bag bellows for air supply. A small furnace was made and then fired with wood fuel. The wood was wet but managed to fuse and partially melt sand in the furnace.

To get better performance, I made charcoal from the poor quality wood. I made a reusable charcoal retort to make it. This was different from the previous reusable mound I built as it consisted of a mud cylinder with air holes around the base. To use, it was stacked with wood and the top was covered with mud as opposed to the previous design which had a side door. The fire was lit from the top as usual and when the fire reached the air entries at the base (after an hour or two) the holes were sealed and the mound left to cool. The top was the broken open the next day and the charcoal removed. Another batch was made using significantly less effort as the main structure of the mound did not need to be rebuilt each time, only the top.

Iron bacteria was again used to test the furnace. Charcoal and ore was placed in the furnace and the blower utilised. After an hour of operation the furnace was left to cool. The next day the furnace was opened and only slag was found with no metallic iron this time. I think increasing the ratio of charcoal to ore might increase the temperature so that the slag flows better. Further experiments will be needed before I get used to the new materials here.

The new area I’m in is significantly wetter than the old area and this has affected the order in which I create my pyro technology. The old spot was a dry eucalypt forest with an abundant source of energy dense fire wood. As a result, I developed kilns early on, powered with wood fuel and a natural draft, before developing charcoal fuelled forced air furnaces. In contrast, the new area is a wet tropical rainforest, where wood rots nearly as soon as it falls off the tree in the damp conditions. Wood is also more difficult to collect here because of hordes of mosquitoes (away from the fire) and unpleasant, spiky plants. Because of this I developed a forge blower first as it allows higher temperatures from a lower quantity and quality of fuel.

This poor quality wood can further be improved by converting it to charcoal first. In future, it may be necessary to cut fire wood green and dry it as opposed to picking it up off the ground dead as was preferable in the Eucalyptus forest I came from. The blower is also handy for stoking a tired campfire back into flames, I simply scrape the coals into a small mound around the nose of the tuyere and spin the impellor. I use the blower each day I’m at the hut for this purpose to save blowing on hot coals each time I need a fire for something.

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