Earth Oven: Numero Cuatro

Sticking with my tradition of starting and finishing ovens days before leaving the site, I joined David Slocum at his healing and cleansing center, Amaru Spirit, to build him an earthen oven. I only had five days, no base, and insufficient materials. Pucha.

It was late November, just at the tail end of the dry season in Iquitos, Loreto, Perú when I arrived. I had sent David my instructions and a diagram for building the oven six-months earlier. But, like most of my clients, there’s a general uncertainty surrounding how to make earthen ovens that prevented him from jumping in, and he decided to wait until I was available to lead the job.

I hoped that David would’ve had at least the base built before I arrived, especially after I sent another set of instructions. Unfortunately, that didn’t materialize, but he did build the main deck, and had most of the ingredients I requested.

After arriving on a very slow peque-peque (a 3hp canoe) I walked to the house to survey the situation. After inventorying our supplies I knew we’d need a lot more clay and sand. With my time crunched due to the unexpected base construction, I immediately got to work hauling supplies to the staging area on the deck. While lifting 40-kilo sacks of sand up a ladder, I brainstormed options for the foundation.

David built a nice square platform off the edge of the main deck for the oven. I used that space to start visualizing how to approach the building the foundation. During the construction of my third earthen oven at Paititi, I found that one could isolate a great deal of the oven floors contact with the base. This is important because of the possible heat conduction from the oven into the foundation.

A few hours later, David arrived and we discussed our plan of action and material options for the base. I wanted to do three heavy-duty shungos (hardwoods) for the piers/columns with the support beams in hardwood as well. David, having built over half-a-dozen structures on his property, was keen on incorporating anything other than wood. So, we compromised and built a lower base out of brick and cement upon which rests three large shungo beams.

Working in the jungle and in a foreign language, especially one so rife with idiosyncratic slang, is a challenge. Thankfully, I had spent about five-months working side-by-side with many Loretanos that I was actually feeling quite comfortable communicating without too many errors or miscommunication.

That euphoria of cultural melding was quickly thrashed after I saw Slocum’s eyes bug out when he realized that his workers chainsawed a 10-meter shungo. Shungos are increasingly difficult to obtain in the Amazon, especially near large population centers like Iquitos. People are traveling farther and farther into the virgin forest to fell giant beauties like huacapú, pali perro, ana caspi, and dozens of other dense, durable and usually rot/termite resistant woods. With global consumption on the rise, the prices for these pieces rise as well.

Getting the shungo to his property took much finagling. The community where it was harvested was remote and took a lot of time to establish a trusting relationship; it needed 10-men to carry it; and a boat capable of navigating the twisted Amazon rivers till it arrived at his land. To add to his dismay, the post was also to be a central piece in a new house he was designing. We were not off to a great start.

Steel decking for an earthen oven base

The last oven I built was constructed on top of a poured concrete base supported by a formwork on five 4”-diameter legs. I like to use a minimal amount of concrete, if any, and thought that steel decking would be a great solution for trying to support the multi-ton oven without building with concrete.

Usually, with steel decking, the decking is welded and laid over steel trusses or beams. Concrete is then poured onto the decking at a certain width and is embedded with steel rebar to add tensile strength. This allows builders to use less concrete, saving on weight and material costs. In lieu of cement, I thought that I could use the oven mud mix (3 sand, 1 clay) over the decking. Trouble was, the sheet was still in its original rectangular form and needed cutting and welding. All of which required it to be transported back to Iquitos. Did I mention that I needed it yesterday?

With the time crunch upon us, I was unsure if we could actually pull off building a three-foot-diameter oven. We had the hands, but the clouds began pouring rain, off-and-on, during the first two days. Each downpour was a mad scramble to cover the brick foundation’s progress and secure the remaining materials from blowing away. All we could do was wait it out until the clouds and rain cleared.

Thankfully, David was able to get the steel decking cut exactly to my specs, leaving us with a roughly 5’ x 5’ solid piece of steel. The rains also let up a bit to allow us to finish the brick base with enough time to let it set before starting the shungo foundation box.

While progress advanced on the bricks, I set about starting to sketch out the arches for the both the foundation box and the oven door. Making arch forms is a bit of a challenge, and I look forward to the day where I don’t have to make recuts. I’m also at a bit of a handicap working in the jungle with limited power-tools, and would make light of the work in the states.

I’m not one to enjoy idling when working on projects. There’s always something that can be done on site, even if it’s simple cleanup and tidying. Before the bricks were ready to support the oven construction, I prepped bottles, mud mixes and the shungo measurements/cuts for the base plate. This prep allowed us to transition smoothly into the next phase of building which was very important given our schedule pressures.

Base Is Done, Now We Build

The brick arch in the lower section turned out quite nice. The idea originally was to use it as a dry area for firewood for the oven. But Gaia, David’s dog, quickly saw the real use for it and made it her home. It was, in fact, a perfect dog house. The brick was shaded from the sun, thus radiated cool air in the hot early-afternoon and the large shungo beams, each about 8” tall, had large gaps between them allowing cool breezes to waft through. I even climbed in to test the comfort level. Though a bit claustrophobic, it was a welcome respite from the brutal sun.

We nailed in large tablas made of shungos into the beams to form a box with the steel decking resting inside. Only David’s guardian, Bony, was able to sink the 5” steel nails into the exceptionally dense wood.

With the box secure, we were able to begin laying in the oven mud to begin the foundation.

A cool thing happened as we mixed bucket after bucket of clay, sand and water together. I had been noticing these strange, flat clear pieces of what I thought was plastic. The workers had hauled the clay from a river bank near Iquitos, so I assumed it was some sort of plastic refuse that had been dumped and was mixed in. Each time I encountered one, I would toss it deep into the jungle to live out its 100,000+years of decomposition.

It took David, mixing and dancing the clay with us, to realize that what I originally thought was plastic was actually quartz. The clay we were sourcing was filled with these crystals! The best part was David had wanted to include a few crystals in the oven mud before finding the native crystals. As we mixed more batches, we uncovered so many crystals that we stopped pausing to remove them and instead let them be a part of the oven.

Aislante, Mucho Aislante

Another materials item we were lacking were glass bottles. David had picked up a few bags, but we were lacking about 100-150 glass bottles. During David’s outing for the steel decking, he chanced upon a man who had bags of old, reusable glass bottles stored in the attic of an old rubber baron’s mansion. As we cleaned off the bottles, we got a very fun snapshot into Iquito’s soda brands and offerings.

With a few of the bottles removed for David’s collection, we laid the rest in the insulation mud mix (roughly 1:1, clay:sawdust). Yolita, Greg, Katie, and Rodrigo helped get us through the layering stages, as well as Lider, Teddie and Teddie’s son. Kametza even got in on the act dancing in the mud and handing us mud balls.

I had built the oven larger than I expected to. Instead of doing a 30” or 32” diameter oven, I opted for going big and designed it for 36”. This meant a vary large amount of mud was needed to build the thick walls. Dancing in the tropical rainforest heat is not easy, but, thankfully, David and Yolita made us many delicious camu camu refrescos and awesome spirulina-avocado-cacao-y-más smoothies to power us through. What the drinks didn’t replenish, the amazing meals, made by Yolanda, did.

Almost Finished, Almost

Working from dawn to dusk, and even a bit into the night despite the hordes of mosquitos nipping at my unprotected legs, we managed to finish all three caps of mud on the monstruous oven.

Unfortunately, and I take blame for not being more adamant on having it built, we did not have a roof to protect the oven. Instead, we relied on plastic sheeting placed over the oven at the end of each day to protect from evening rains. A very large drawback to this, especially in a humid tropical environment, was that the plastic also prevented the oven from losing moisture.

The first signs of error and potential collapse were seen in the bulging of the layers as we applied more mass to the structure and reached the final coating. Ideally in a humid environment, you build layer-by-layer with some “breathing” time in-between — roughly 3-7 days. But, being under the gun and wanting to get the bulk of the oven done under my supervision, we laid all three layers.

I think it wouldn’t have been an issue had we had a roof over the structure from the start. But, that wasn’t the case and I couldn’t stay longer to supervise the removal of the sand form. I left instructions on how to finish the oven prep process, including starting the first fires. Much to my dismay, those final steps were never reached because the layers started slumping and David wrote me of significant chunks of mud coming off and large cracks forming. I asked for photos so I could diagnose the issue and offer a remedy, but none came my way.

The fact that the oven was covered by plastic, got hit exposed by a few rain showers and was built rapidly made for a lot of movement in the layers, leading to the structural cracking and damage.

A month later I got another email from him saying that sections of the interior collapsed when they were excavating the last of the sand. I haven’t heard how it’s fairing, or if they were forced to dismantle the oven and reconstruct it. If they did have to rebuild it, at least they can dance their way to a new oven using the same ingredients.