"Since the quality of the clay is not a problem, and we already have a crucial kiln grate, the next step is to officially construct the ground-updraft kiln."
He returned once more to the previously chosen plot of land. The earthen kiln to be constructed doesn't need to be large; being able to fire around twenty clay bricks at a time is enough.
This not only ensures heating efficiency but is also convenient for him to operate alone. Lin Yu'an began constructing the earthen kiln based on the blueprint in his mind.
First, he used stones and prepared clay to excavate a foundation pit along the cleaned circular ground's edge, then built a low ring-shaped foundation wall with an inner diameter of about sixty centimeters, which would serve as the base for the entire kiln.
Next, he reserved a gap about twenty centimeters wide on one side of this foundation wall, serving as the firewood addition opening and air inlet.
Then came the installation of the successfully fired ceramic grate. He carefully set the ceramic grate on the inner side of the foundation wall, ensuring it remained level and stable.
This grate would play an important role in separating the firebox from the kiln chamber, supporting the brick blanks, and allowing heat to pass through.
After the grate was properly positioned, Lin Yu'an began using the prepared clay mixed with a large amount of chopped dry thatch to build the kiln chamber walls upward along the edge of the grate.
He constructed the kiln chamber walls into a roughly vertical cylindrical shape, making the inner walls as smooth as possible, with a height of about sixty to seventy centimeters, intending to load and unload materials directly from the top of the kiln.
"The kiln walls don't need to be too thick, ten to fifteen centimeters is enough; it heats up quickly and saves fuel," Lin Yu'an explained as he built.
When the kiln chamber walls were built to the planned height, this earthen kiln resembled a sturdy open-top clay pot.
The top of the kiln was an open circular hole with a diameter of about sixty centimeters, which served as both the loading entrance for brick blanks and a window for smoke discharge and observations during firing. When sealing the kiln is necessary, it would also be covered with ceramic panels.
The main structure of the earthen kiln, after an afternoon of Lin Yu'an's diligent work, took shape.
"Alright, the main body of the kiln is done! Now, it still needs time to naturally air-dry, allowing the moisture in the clay to slowly evaporate."
Lin Yu'an patted the kiln wall, which was still damp, and said, "During this time, we can make a mold for the brick blanks and ceramic panels to seal the kiln top."
Lin Yu'an had hardly rested these days; if it weren't for the recent catch of fish relieving his food worries, the progress wouldn't have been so fast.
Taking advantage of the remaining daylight, he immediately turned to the next task, starting to make the clay brick mold.
"The mold size is initially set to twenty centimeters long, ten centimeters wide, and five centimeters high."
As he spoke, Lin Yu'an meticulously shaped, cut, and assembled the prepared clay into a hollow, rectangular box that met the preset dimensions of the inner walls.
Next, he used clay to make several rectangular clay panels about two or three centimeters thick, carefully smoothing the edges of the panels.
"Once these panels have air-dried and fired, they'll be used to seal the kiln top, and they need to be sealed tightly once assembled."
After completing the mold and kiln top sealing panels, Lin Yu'an placed them in a ventilated and dry corner of his shelter for natural air-drying.
Two days passed, and the clay on the surface of the earthen kiln felt considerably dry to the touch, while the clay mold and several kiln top sealing panels had also air-dried and hardened.
Knowing he could proceed with the final treatment of the kiln body, Lin Yu'an explained to the camera.
"It's time to perform a low-temperature bake on the kiln body."
"The purpose is the same as when making the grate - to thoroughly remove residual moisture inside the kiln walls and let the clay initially sinter to increase the kiln body's strength."
From nearby, he collected some dry small twigs and kindling, carefully lighting a small flame in the firebox at the bottom of the earthen kiln.
He allowed the weak flame and heat to gradually bake the kiln walls, while the top of the kiln remained open for full water vapor dissipation.
This time Lin Yu'an started the kiln firing in the morning, with small fires burning for several hours before gradually shifting to large fires, continuing until midnight.
Only when he judged that the kiln body was properly dried and preliminarily sintered did he gradually extinguish the fire, allowing it to naturally cool overnight.
On the twenty-third day, although Lin Yu'an caught roughly one small fish every day these days, the program team's requirement was to catch no more than two fish per day on average during the early stages.
Thus, his food consumption was rather fast, showing signs of running out. He needed to speed up to complete this project!
During this time, he was deeply immersed in the challenge, trying his best not to cheat spatially, relying solely on his own abilities.
"Good morning, my ground-updraft kiln, today you are officially completed and ready for use!"
"With the new kiln built, the first fire will be used to fire this clay brick mold and those few kiln top sealing panels."
Lin Yu'an patted the warm kiln wall, eyes filled with anticipation.
He picked up the already air-dried clay mold and panels, carefully placing them on the ceramic grate in the center of the kiln chamber via the top opening, leaving gaps to promote heat flow.
Then he began adding firewood to the firebox below.
This firing, he was extra cautious, aiming for success in one go! During the small fire preheat stage, he patiently waited, observing the steam rising from the kiln top opening.
About two hours later, when the steam disappeared, he began gradually increasing the firepower.
The flame roared inside the kiln, and the thermal insulation was far better than the previous open fire pit.
Lin Yu'an continued to add dry wood, judging the temperature inside the kiln by observing the flame color and smoke conditions at the kiln top.
When the flame turned bright orange and there was almost no black smoke at the kiln top, with only transparent heat waves visible, he knew that the temperature had reached the level necessary for sintering ceramics.
This high-temperature firing lasted about seven to eight hours.
Lin Yu'an stopped adding wood, allowing the remaining wood in the firebox to burn to charcoal, then carefully placed the air-dried ceramic panels piece by piece over the kiln top opening.
He then used wet clay to seal the gaps between the panels and the edges touching the kiln walls, as well as closing off the firewood addition opening, commencing "kiln wrapping."
Another night passed, and when the kiln body was completely cooled down, Lin Yu'an, with a trace of nervousness and anticipation, gently removed the sealing clay panels with visible cracks from the kiln top.
Yet there were quite a few pieces of clay that fell into the kiln chamber, fortunately without much impact.
Lin Yu'an reached into the kiln to retrieve the clay mold and several ceramic panels. They produced a clear "knock knock" sound when struck.
Excitedly showcasing to the camera: "Another success! Folks, look at this! I think I could operate a ceramic studio someday!"
"The clay brick mold and the kiln top sealing panels, all perfectly fired in one go! Although the mold's edges are a bit uneven, the flatness of these panels is pretty decent!"
"Plus, my fire kiln has thoroughly vitrified, resistant to rain erosion, but I still need to build a rain shelter for placing clay brick blanks."