"My plan is this: we need to fire clay bricks for the furnace, so the first step is to find suitable clay and build an earthen kiln!"
Lin Yu'an picked up the camera, brought along a logging axe and a sharp wooden spear, and began his quest for soil.
While fishing earlier, he noticed that the direction in which the lake water was flowing was the north bank of the river. Such places often form fine clay layers due to the scouring and deposition of water flow.
Sure enough, at the inside of a riverbend, he found a patch of fine-textured, reddish soil.
He dug out a piece and kneaded it in his hand.
"This clay has excellent malleability, and there are almost no sand and stone impurities. With a bit of processing, it's an excellent raw material for pottery!"
After finding the pottery clay, the next step was choosing a site for the kiln. He chose a flat open space about a hundred meters away from the riverbend, slightly elevated in terrain.
It was convenient to collect firewood and clay here. Lin Yu'an roughly sketched out the outline of the earthen kiln on the ground with a wooden spear, with a clear blueprint in his mind.
As he cleared out a round, flat area about one meter in diameter, he explained to the audience.
"I plan to build the firechamber and kiln chamber directly on the ground, constructing an updraft earthen kiln where the flame rises from bottom to top."
With the blueprint complete, Lin Yu'an didn't hesitate and immediately threw himself into the intense labor.
Before starting the construction of the kiln, he needed to test if the clay here could successfully fire pottery.
On a relatively flat stone, Lin Yu'an kneaded and pounded a piece of clay repeatedly like dough.
After several hours and multiple failures in forming, a rough round 'grid' finally started taking shape in his hands! Lin Yu'an placed it aside to air dry.
Today, the wind was slightly strong, but by evening the wind had calmed, and the grid had turned somewhat white, which suggested it was ready for firing.
Lin Yu'an started a fire in a U-shaped fire pit surrounded by stones. Flames immediately leaped among the dry firewood, making a crackling sound.
He carefully picked up the air-dried round clay grid and gently placed it above the fire pit, resting it flat on stones on either side.
"Now we begin firing this grid! If it successfully turns into ceramics, then the key component of our furnace is secured!"
The open fire pit, though not as hot as an earthen kiln, is sufficient to sinter such a single piece without high precision requirements.
The flames grew stronger as Lin Yu'an continuously added dry fine kindling to the fire pit, ensuring the flames evenly touched the base of the grid.
He was careful not to let the flames grow too violently, worrying that a sudden increase in temperature might cause the grid to crack.
He explained to the camera: "The first step of firing pottery is to slowly remove any remaining moisture. Although this grid has air-dried, there is still a trace amount of moisture inside."
As time passed, under the flames' roasting, the color of the grid began to change subtly.
Lin Yu'an observed intently, occasionally stirring the firewood in the pit to ensure the grid heated evenly.
After about two hours, he judged that most of the remaining moisture inside the grid should have evaporated.
He began gradually increasing the heat, adding more and thicker firewood into the fire pit.
The flames leaped more fiercely upwards, enveloping the entire grid, with the warm red light reflecting on Lin Yu'an's face.
He could smell a distinctive odor of burning earth, a signal that the clay was undergoing chemical changes at high temperatures.
This was a critical stage: minerals in the clay melt and recrystallize under high heat, forming a hard ceramic structure.
Lin Yu'an needed to maintain this high temperature for as long as possible to ensure the grid would fully sinter, conservatively estimating it would take until the next morning.
He managed his expectations, not planning on immediate success. He just wanted to experiment to see if this clay could turn into pottery, even if just pottery shards.
Nearly two hours of continuous firewood adding kept the fire pit flames vigorous, and thankfully, he had prepared enough dry wood to last until the next morning.
Night had fully descended.
The fire pit flames became the sole flickering light source in the darkness.
Lin Yu'an occasionally stood up to stretch his stiff limbs, then sat back by the fire pit, picking out suitably sized dry wood from the nearby pile and carefully feeding it into the fire.
With each addition, he observed the state of the flames closely to ensure they weren't too intense, risking cracking the clay body, nor too weak to affect the temperature.
Time quietly passed amid the crackling of firewood.
From midnight to dawn, and then to the first light of day, Lin Yu'an stayed awake, constantly watching the fire pit.
His stockpile of dry wood was more than half consumed, the pile noticeably diminished.
Lin Yu'an spoke with anticipation in his voice: "It's daylight, it feels about right."
"To ensure thorough firing, I plan to give it another push and fire until noon."
He added more wood a few more times, keeping the fire at an appropriate level.
By around noon, Lin Yu'an stopped adding wood. Since the previous evening, this clay grid had been in constant high-temperature firing for over fifteen to sixteen hours.
Such duration for a single piece fired in a fire pit should suffice for it to fully sinter.
Lin Yu'an announced: "Alright, the high-temperature firing phase is over!"
He didn't immediately remove the grid from the flames but allowed the remaining firewood in the pit to naturally burn out into a pile of red-hot charcoal.
This charcoal would continue providing stable residual heat, allowing the clay grid to cool down slowly, a crucial step to prevent cracking due to sudden temperature changes.
He stretched wearily, the sleepless night and continuous physical exertion making him feel physically drained.
He returned to the stone shelter and had a well-deserved sleep.
Lin Yu'an slept deeply, exhausted from the sleepless night like a tide engulfing him.
About three hours later, a chill woke him.
He sat up abruptly, shaking his head in a daze, and his first thought was of the clay grid cooling outside!
Rubbing his sleepy eyes, he quickly walked to the fire pit from the previous night.
After half a day of natural cooling from the wind, the thick layer of charcoal ash covering the grid had become gently warm.
Lin Yu'an crouched down, carefully using a stick to brush away the surface ashes. As the ashes were slowly cleared, the clay grid buried beneath began to emerge.
As the entire clay grid was fully exposed to the air, a burst of surprise lit up in Lin Yu'an's eyes! This clay grid far exceeded his expectations!
The clay grid not only retained its form well but didn't show the severe cracking or deformation he feared.
Although not as bright as modern glazed pottery, that refined roughness definitely belonged within the realm of pottery!
Lin Yu'an carefully picked up the clay grid from the ashes. It was sturdier than he imagined, and he gently tapped its surface with his knuckle.
"Ding! Ding! Ding!"
The clear and melodious sound it emitted undoubtedly proved it had reached an excellent degree of sintering!
"Unbelievable! It succeeded on the first try!"
Lin Yu'an excitedly held up the clay grid to the camera: "Did you see this? It not only proved it could turn into pottery, but the intact texture far exceeded my expectations!"
"I originally just intended this as an experiment, just to confirm if it could become pottery, and was fully prepared for it to crack and break."
"I didn't expect it to form so perfectly! It gave me a huge surprise!"
He carefully stored this precious clay grid, planning to use it during the construction of the kiln.
This successfully fired clay grid not only confirmed the feasibility of making clay bricks but also greatly boosted Lin Yu'an's confidence in completing this large project!