HUN Chapter 19: Firing Brick Blanks

"Since the clay quality is fine and we already have a key kiln grate, next we can officially build the ground updraft kiln."

He returned to the previously selected clearing. The earthen kiln he planned to build didn't need to be too large, capable of firing about twenty clay bricks at once would be sufficient.

This would ensure heating efficiency while being convenient for one person to operate. Lin Yu'an began building the earthen kiln according to his mental blueprint.

First, using stones and mixed clay, he dug foundation pits along the edge of the cleared circular ground, then built a low circular wall foundation with an inner diameter of about sixty centimeters, which would serve as the base for the entire kiln body.

Next, he left a gap about twenty centimeters wide on one side of this circular wall foundation to serve as the wood-feeding and air intake opening.

Then came installing the successfully fired pottery grate. He carefully positioned the pottery grate on the inner side of the circular wall foundation, ensuring it remained level and stable.

This grate would play the important role of separating the firebox from the kiln chamber, supporting the brick blanks and allowing hot air to pass through.

After the grate was properly positioned, Lin Yu'an began using mixed clay combined with large amounts of chopped dry thatch to build up the kiln chamber walls around the grate's edges.

He built 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, planning to load and unload materials directly from the kiln's top.

"The kiln walls don't need to be too thick, ten to fifteen centimeters is enough. This way it heats up quickly and saves fuel," Lin Yu'an explained while building.

When the kiln chamber walls were built to the predetermined height, this earthen kiln looked like a thick pottery jar without a lid.

The kiln's top was an open circular opening about sixty centimeters in diameter. This opening would serve as both the entrance for loading brick blanks later and the window for smoke discharge and observation during firing. When sealing the kiln was needed, it would also be covered with clay plates.

The entire earthen kiln's main structure took initial shape under Lin Yu'an's diligent afternoon work.

"Alright, the kiln's main body is basically complete! Now, it still needs time to air dry naturally, letting the moisture in the clay slowly evaporate."

Lin Yu'an patted the still-damp kiln wall and said, "While we're waiting, we can perfectly make a mold for creating brick blanks, as well as clay plates for sealing the kiln top."

Lin Yu'an had barely rested for a moment these past few days. If not for his fish catches from earlier allowing him not to worry about food, progress definitely wouldn't have been this fast.

Taking advantage of the remaining daylight, he immediately turned to the next task, beginning to make the clay brick mold.

"For the mold dimensions, I initially set them at twenty centimeters long, ten centimeters wide, and five centimeters high."

While speaking, Lin Yu'an carefully patted, cut, and joined the mixed clay into a hollow rectangular box with inner wall dimensions matching his preset specifications.

Next, he used clay to make several rectangular mud plates about two to three centimeters thick, carefully smoothing the plates' edges.

"After these mud plates air dry and fire, they'll become our kiln top sealing covers, and when pieced together they need to be as airtight as possible."

After completing the mold and kiln top sealing plates, Lin Yu'an placed them in a well-ventilated, dry corner of the shelter to begin natural air drying.

Two days passed. The clay on the earthen kiln's surface felt much drier to the touch, and the clay mold and several kiln top sealing plates had also air-dried and hardened.

Lin Yu'an knew it was time for the kiln body's final treatment. He explained to the camera.

"It's time to perform low-temperature baking 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 preliminarily sinter, increasing the kiln body's strength."

He collected some dry, small dead branches and tinder from nearby, carefully lighting a small pile of flames in the firebox at the earthen kiln's bottom.

He let the weak flames and hot air slowly bake the kiln walls. The kiln's top was open at this time to allow water vapor to fully dissipate.

This time Lin Yu'an started firing the kiln in the morning. After burning with a small fire for several hours, he began high-temperature firing, continuing until late at night.

After Lin Yu'an judged that the kiln body had fully dried and preliminarily sintered, he gradually reduced the fire and let it cool naturally overnight.

On the twenty-third day, although Lin Yu'an had been catching about one small fish daily these past days, the program's requirements stated that early-stage average daily fishing couldn't exceed two fish.

So his food consumption was still somewhat fast, with a tendency to run out. He needed to speed up to perfect this project!

During this period, he had completely immersed himself in this challenge, trying as much as possible not to cheat with his space ability, relying entirely on his own capabilities.

"Good morning, my ground updraft kiln. Today it's officially completed and ready for use!"

"With the new kiln built, for the first firing, we'll use it to fire this clay brick mold and those kiln top sealing plates."

Lin Yu'an patted the warm kiln wall, his eyes full of anticipation.

He picked up the air-dried clay mold and mud plates, carefully placing them through the kiln's top opening into the center of the kiln chamber above the pottery grate, leaving gaps to facilitate hot air circulation.

Then he began adding firewood to the firebox below.

For this firing, he was especially cautious, still hoping to succeed on the first try! During the small fire preheating stage, he patiently waited and observed the water vapor emerging from the kiln top opening.

After about two hours, the water vapor disappeared and he began gradually increasing the fire intensity.

Flames burned vigorously inside the kiln. The earthen kiln's heat retention was much better than the previous open fire pit.

Lin Yu'an continuously added dry firewood, judging the kiln's internal temperature by observing the color of flames at the kiln top and the state of smoke.

When the flames turned bright orange-yellow and almost no black smoke could be seen at the kiln top, only transparent heat waves, he knew the temperature had reached the level needed for sintering pottery.

This high-temperature calcining lasted about seven to eight hours.

Lin Yu'an stopped adding firewood. After letting the remaining wood in the firebox burn into charcoal, he carefully placed the air-dried, backup clay plates one by one over the kiln top opening.

Then he used some wet clay to seal the gaps between the mud plates and the edges where they contacted the kiln walls, while also sealing the wood-feeding opening, beginning the "smothering kiln" process.

After another night, when the kiln body had completely cooled down, Lin Yu'an, with a mix of nervousness and anticipation, carefully removed the sealing mud plates from the kiln top, which now had several cracks and fissures.

But there were still quite a few mud fragments that fell into the kiln chamber, though fortunately the impact wasn't significant.

Lin Yu'an reached into the kiln and retrieved the clay mold and several clay plates. When tapped, they also produced clear "knock knock" sounds.

He excitedly showed them to the camera, "Success again! Guys, look! I think I could run a ceramic workshop after this!"

"The clay brick mold and the clay plates for sealing the kiln top all fired perfectly in one go! Although this mold's edges are still a bit irregular, these clay plates have quite good flatness!"

"And my kiln has been thoroughly ceramicized, no longer afraid of rain erosion. But I still need to build a rain shelter to store the clay brick blanks."

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