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I smelted iron bacteria in a short furnace and produced a small quantity of iron prills (small iron spheres). In my ongoing quest to reach the iron age, further experiments were conducted concerning furnace design and the treatment of ore. I began by making a very short furnace. A pit 25 cm wide and 25 cm deep was dug and the tuyere of the forge blower placed in a 15 degree downward angle into the pit. Onto this, a furnace stack made of mud and grass was built 25 cm above ground level. The furnace was fired at various stages to help dry it. It took less than a day to build.
Eucalyptus wood was collected dead off the ground and stacked into a re-useable charcoal mound I had made previously. The top was sealed with mud and the mound lit. It took about 2 hours 30 minutes for fire to reach the air entries, at which time the holes were sealed and the top closed with mud.
Iron bacteria from the creek was gathered and brought to the smelting hut for processing. Charcoal was ground into a powder and mixed with the ore and water in the proportions of 1:1 char to ore by volume. This mixture was formed into 59 pellets 2.5 cm in diameter and then dried on top of the furnace.
To make the smelt, a wood fire was made in the furnace and allowed to burn for about an hour by natural draft and blowing. When the wood burnt down to the tuyere the furnace was filled with charcoal and 10 pellets were added to the top and the blower was engaged. Three handfuls of charcoal and 10 pellets were added at about 7 minute intervals totaling about 42 minutes. Charcoal was then continuously added after the last charge until the basket was empty. It took a total of about 3 hours working the blower until the operation ended.
The mass of slag and iron prills was prized out of the furnace using a log and wooden tongs. It was hammered flat while hot but no large bloom was made. Instead many small iron prills were found. These mostly seemed to be cast iron.
So far this is the largest amount of iron I’ve made in the wild and it used less charcoal than previous attempts, so I consider it a success of sorts. The ore must be mixed with carbon to ensure the correct reduction chemistry normally provided by carbon monoxide in a taller bloomery furnace. The fact that cast iron was produced suggests that next time less charcoal powder be added to the ore pellets or perhaps none at all considering that dead iron bacteria may also contribute some carbon to the ore. Alternatively, cast iron can be re-melted in a “finery” furnace, a small highly oxidizing furnace, to remove excess carbon, producing steel or iron. Alternatively cast iron can be converted into malleable cast iron by heating it in an enclosed container at 800-1000 c for long periods. Further experiments will be conducted.
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I developed an experimental cement from made only from re-fired wood ash as its cementitious material. It was mixed with crushed terracotta as an aggregate and formed into a cube. The cement set hard after 3 days and did not dissolve in water after this period.
Process: First I burnt bark and leaves in a kiln at high temperatures to produce well burnt, mostly white wood ash. The ash was then mixed into water and stirred well. The excess water was poured off and the resulting paste was made into pellets and allowed to dry. A pellet was then re-heated in the forge until it glowed about orange hot. This was then taken out, cooled and dropped in a pot of water. The pellet dissolved and boiled due to a chemical reaction with the water. The paste was stirred and crushed terracotta (old tiles from previous projects) was added and mixed to form a mouldable mortar. This was formed into a cube and allowed to set for three days (in the video, a cube made exactly the same way 3 days previously was used due to time constraints). The resultant cube was strong and made a slight ringing sound when tapped with a finger nail. It was placed in water for 24 hours to simulate a very heavy rain event and did not dissolve or release residues into the water.
My current theory: The main component of wood ash consists of calcium in some form (e.g. calcium carbonate, calcium oxide). This can be up to 45% from my research. Calcium is in higher concentration in the bark and leaves of a tree. When the ash is mixed with water, the soluble component of wood ash (10% pot ash) dissolves into the water. But seeing that it does nothing for the cementing process, it is drained off leaving the insoluble calcium (and other components) in the paste. Doing this probably raises the relative percentage of calcium in the paste to about 50% or more. Most of the other 50 % consists of silica and alumina which are pozzolans, materials that chemically react with calcium hydroxide to increase the durability of the cement product. The paste was then made into a pellet and fired again to high temperature to convert all the calcium compounds to calcium oxide. It also reduces any charcoal in the pellet to ash if it hadn’t already been burnt the first time. This step seemed important as un-fired ash pellets only partially hardened and would fall apart in water, though retaining a weak undissolved 5mm thick crust. I can only surmise that re-firing the ash just gave a greater conversion of the calcium components to calcium oxide. The pellet is slaked in water converting the calcium oxide to calcium hydroxide. This cement was mixed with crushed terracotta which may also help in some way that I’m not aware of as I only did this one experiment and did not test other aggregates yet (e.g. sand, gravel etc.). Terracotta is porous and might hold together better than other materials. The mixture is allowed to set in air where carbon dioxide reacts with calcium hydroxide to form calcium carbonate cementing the aggregate together. After this, the cement will not dissolve in water.
Use: I think this material might have a potential use as a mortar holding rocks or bricks together in wet environments where limestone or snail shells are unavailable for making cement. Wood ash is a pretty ubiquitous material to most natural environments inhabited by people using biomass fuels. Wood ash cement turns a waste product into a valuable building material. From my research, wood ash is already being used as a partial replacement for cement in the building industry without decreases in strength of the final product. But I’ve only just started experimenting with it and don’t know its full capabilities and limitations. Calcium content of wood ash differs depending on the species of tree, the part of the tree burnt and the soil it’s grown on. Cautious experimentation is still required before committing to a hut built from this material.
]]>I planted a yam in a large basket like enclosure and then 6 months later harvested, cooked and ate it. My previous attempts at growing yams were stymied by wild pigs and scrub turkeys. On learning that yams are in the area, these animals will seek out any tubers planted and eat them. So my solution was to build a large basket like enclosure to protect the growing vine. 13 wooden stakes were hammered into the ground (an odd number being important in any weaving project) and lawyer cane harvested from the forest was woven between these uprights. The basket was about 1 m in diameter and about 75 cm high.
A large yam, partially eaten by wallabies from a location further down the creek, was dug up and carried to the site. A small pit was dug in the enclosure and the yam simply placed in it. The enclosure was then back filled with dead leaves for fertiliser. As time progressed the vine grew above the basket and a long pole attached to it so it could climb into the canopy making full use of the sun.
After 6 months and no maintenance, weeding or watering the yam had grown into two large tubers whereas the original yam had rotted away leaving a thin husk. The new tubers were dug up using a digging stick. As carful as I was, the yams sill broke off with more tuber still under ground. This portion will probably strike next season anyway. In the canopy, the vine also produced smaller tubbers called “bulbils”. These were collected in a pot to be used as seed yams for a larger garden I’m planning. You can eat bulbils as well but the larger yam is generally eaten instead due to its larger size.
To cook the yam a fire pit was dug about 30 cm in diameter and about 20 cm deep. Wood was piled above the pit and set alight. The hot coals then fell into the pit where rocks where added to retain heat. The coals were scraped aside and the large tuber was broken up and thrown on top. The coals were raked back over it and a fire started on top. This cooked for 30 minutes before being pulled out of the coals. The outer layer of the yam was charred black and burning but the inside was soft and well cooked. The yam was eaten while steaming hot and tasted similar to a potato but with a crunchier texture near the outside much like bread crust. Although bland, yams provide a good deal of carbohydrates and are eaten as a staple in certain cultures. The remaining large yam tuber was tied up in a tree where rats could not eat it (hopefully).
This form of farming is a good way to get around the conventional farming practice of clearing trees to make fields. Instead the yam vine uses the trees as scaffolding to climb on, allowing it to reach the light in the forest canopy. The basket enclosure worked well to keep forest creatures from eating the investment. It also formed a good in-situ compost heap to nourish the yam as it grew. In future, I’d add sand to the mix as yams tend to do well in sandy soil and I expect it would be easier to dig up. Yams do well in dry conditions but will yield more if well-watered so digging a water retaining pit might help. Despite the large size of the yams I grew relative to ordinary potatoes, much larger ones are possible and are indeed routinely grown. The largest one from my research was 275 kg, grown in India. Yams have 116 calories per 100 grams compared to potatoes at only 93. They store well in the dry season as they are adapted to having a dormant period during these conditions. They are versatile in that they can be cooked into chips, roasted, boiled, mashed and made into a type of dough called “fu fu” typically eaten with stews.
]]>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 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 met 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.
]]>I built a round hut using palm thatch and mud walls to replace the damaged A-frame hut built a few months ago. The A frame hut was damaged due to torrential rain and poor design elements considering the wet conditions. The thatch had rotted in the part of the roof that gets shade. Moth larvae and mold grew and consumed the thatch in these places. The hut also tilted forward due to the back post being hammered in only 25 cm into the ground. So on returning to the property (it was cut off by flooded bridge) I began work on a new hut.
The new hut was positioned further into the open clearing to get more sunlight. A 3 meter diameter circle was scribed and 12 wooden posts were hammered into the ground, each 50 cm deep for a sturdier structure. Lintels were then tied to the top of the posts joining the posts together. A tripod ladder was made from poles lashed together at the top and a platform lashed to its frame. The roof poles were then attached to the top of the lintels and lashed together at the top to form a conical roof frame, 3 meters at the highest point. Loya cane was then tied on the eaves to act as support for the ends of the palm thatch.
700 palm fronds were then cut split and thatched onto the roof. The tripod ladder was used to climb up and thatch the roof from the inside. A cap was then made to put on the very top of the cone when the roof was almost finished.
A drainage moat was dug around the hut and the excavated soil was placed on the hut floor to raise its level above the damp ground. A deluge tested the hut’s water shedding abilities. Torrential rain fell while a fire was kept going inside the dry hut. The drainage moat flowed like a stream during the heavy rain event.
Loya cane was then harvested and woven between the posts. This formed a low wall. It was then daubed with mud inside and out. The clay from this was taken from the drainage moat. Rain falling into the moat meant that water didn’t need to be collected from the stream to mix the mud. This is another benefit of the drainage moat.
The low wall allows light and air into the hut. With a fire going in the central pit, mosquitoes are kept at bay. The central fire pit produces smoke and heat that will hopefully prevent moths laying eggs in the roof (the caterpillars of which eat thatch) and will prevent mold from growing. The hut will be used as an undercover work space for future projects.
]]>At the old hut site (the new one being temporarily cut off by flooding) I made lime mortar from the shells of rainforest snails by firing them in a kiln, slaking them in water, mixing them into lime putty. Lime is basically calcium carbonate (CaCO3). The general source of lime is limestone and various other calcareous minerals, though shells, egg shells and coral are other sources of lime. When heated above 840 degrees Celsius, the lime decomposes into calcium oxide (CaO) or Quicklime and releases carbon dioxide (CO2). When water is added to the quicklime it becomes calcium hydroxide Ca (OH)2 or lime putty. From here the calcium hydroxide can then be shaped into a form and allowed to set. Carbon dioxide enters the lime putty as it dries causing it to turn back into calcium carbonate. The new calcium carbonate has then set, remaining solid and water resistant.
In my local geography, calcareous rocks such as limestone are absent leading to a difficulty in acquiring the feed stock for lime making. However, I was still able to make lime by collecting the shells of large terrestrial snails that are native to the rainforest here. The unoccupied shells of these snails were gathered up and stored at the hut. Fire wood was gathered and packed neatly into the kiln. Importantly, the firewood was stacked on top of the grate rather than underneath it in the firebox as is the normal procedure for firing pottery. Using an ordinary updraft pottery kiln in this configuration allows it to reach much higher temperatures than would be possible during normal use. The wood was lit from above and the fire burned down towards the grate. Alternate layers of shells and wood were added on to this burning fuel bed. After adding the last layer of wood to act as a “lid” to prevent heat loss from above I left the kiln to finish on its own, unsupervised. The whole process took about an hour and a half.
When the kiln had cooled down a few hours later, I took out the calcined shells. Not shown in the video was the fact that some shells got so hot, the dirt stuck to them turned into slag and fused to them, possibly with the lime acting a flux lowering its melting point. This extreme heat (+1200 c) should be avoided as the over burnt lime becomes “dead lime”, unable to slake in water. Most shells were still useable though. They were taken out of the kiln and had water added to them. An exothermic reaction then ensued. Heat was produced as the lime quicklime turned into slaked lime. The water heated up creating steam and the shells decomposed into a white paste. The paste was stirred and crushed pottery was added to it as an aggregate (sand is normally used for this, I just had a lot of old pot sherds lying about to dispose of). This lime mortar mixture was then formed into a block shape and left to dry. It took about a week and a half to set as we have had extremely humid, wet weather. The block was observed to have set demonstrating its properties.
What I created is actually lime mortar, typically used for mortaring bricks and tiles together. It’s basically the ‘Glue’ that holds together the building blocks of masonry structures. From my research 20 kg of lime mortar is used on a 1 m square section of brick wall. 5 kg of lime to 15 kg of aggregate (sand, grog etc.) per a 1 m square section of bricks. The shells, though large, are not terribly abundant. A method for finding shells efficiently needs to be made before considering making lime mortar in this fashion. From my experience sand bars in a creek sometimes accumulate snail shells from higher up in the mountains. In these spots, water velocity decreases and shells in the water tend to drop out of the water column. Additionally lime may be partially replaced with ordinary wood ash in mortar without a corresponding decrease in strength. To conclude, making lime in a land without limestone is possible but can be problematic when trying to do so on a large scale.
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