After solving basic needs such as food, safety, and initial entertainment and spiritual sustenance, Lin Feng's pursuit of quality of life began to shift towards a deeper level of comfort.
Although the wooden house was sturdy and could shelter from the wind and rain, the few window openings covered with animal hides were always a thorn in Lin Feng's side.
During the day, the limited light entering the house makes it appear somewhat dim most of the time.
At night, even with a fireplace and oil lamp, I always felt that I wasn't completely isolated from the outside world, and I couldn't observe what was happening outside in a safe manner.
"If only there were glass windows..." Once this thought took root, it grew wildly in Lin Feng's mind.
He was not without experience in glassmaking. That rough glass he had made earlier was his first successful attempt.
However, cups are small and do not require high flatness or transparency of the glass. Window glass, on the other hand, presents a completely different level of challenge.
It requires a larger, relatively flat, and sufficiently transparent glass plate. This not only places higher demands on material proportions, melting temperatures, and blowing techniques, but also poses a severe challenge to the shaping and annealing processes.
"This will be a huge project."
Lin Feng took a deep breath, his eyes filled with determination and anticipation.
He knew it would take a lot of time and energy, and he might even face countless failures, but he longed for the warmth of sunlight streaming through the clear glass into the wooden house.
So this time he collected far more sand than ever before, washed it repeatedly with stream water, and patiently filtered out impurities and organic matter. Then he spread it on a flat stone slab until the scorching sun dried it completely.
He also put a lot of thought into the wood ash used as flux.
He specifically selected several types of hardwoods that he believed would produce the purest ash after burning, as well as several special plants that had been used to extract alkaline substances, and placed them in a newly built stone stove for full combustion.
The collected ash was dissolved in water, and the carbon black and unburned residue were carefully filtered out. The clear filtrate was then placed in an earthenware pot and slowly simmered and evaporated over a low flame. What was finally extracted was a white alkaline powder that was much purer than before.
He understood that the purity and type of flux directly affected the melting point and final transparency of the glass.
With everything ready, Lin Feng calmed his mind and began making the glass.
He renovated and expanded the previous high-temperature kiln, reinforced the kiln walls with new mud, and improved the ventilation structure, all in order to achieve higher temperatures and more stable control when melting gold fossils.
He sculpted a refractory clay crucible that was larger than any he had ever made before, and the inner wall was carefully coated with a layer of kaolin to prevent adverse chemical reactions between the molten glass and the crucible body.
The raw materials, mixed in precise proportions, are carefully placed into a crucible and then steadily transferred into the kiln.
The moment the flames rose, the temperature of the entire venue changed.
Lin Feng tirelessly pulled the animal-hide bellows, continuously pumping the biting air into the furnace.
Wangcai squatted to one side, curiously watching its owner working hard and sweating profusely, while Meiying lay far away at the door of the wooden house, its eerie green eyes filled with an innate wariness of the scorching kiln.
Time passed amidst the crackling of the flames, and the temperature inside the kiln continued to rise.
Lin Feng would occasionally peer through the observation holes left on the kiln wall to examine the transformation of the ordinary sand and stones inside the crucible.
The mixture gradually sintered from loose powder, its color deepening accordingly. He kept adding the finest firewood, the bellows pumping faster and faster, his animal hide clothes soaked with sweat, his face flushed red in the kiln fire.
Finally, after being roasted at high temperatures for several hours, the mixture in the crucible completely gave way, slowly transforming from a viscous paste into a flowing, bubbly molten glass.
When the viscosity and temperature of the molten glass reach a delicate balance, the most crucial step—blowing and shaping—finally arrives.
He took out the carefully prepared ironwood blowpipe, the front end of which was also reinforced with refractory clay.
He took a deep breath, cleared his mind of distractions, and carefully dipped the blowpipe into the crucible, taking a fist-sized amount of viscous, dripping molten glass.
First came the rolling and initial blowing. He quickly placed the blowpipe containing molten glass on a preheated, flat stone slab and rolled it to make it initially regular. Then he began to slowly blow air into it, and a hollow glass bubble gradually formed under his breath.
The subsequent sizing and stretching are crucial for making the flat plate.
Instead of relying primarily on rotation as in glassblowing, he tilts the blowpipe slightly, cleverly utilizing gravity to allow the molten glass to slowly descend and stretch under continuous and stable blowing, gradually expanding into an irregular, pancake-like shape.
During this process, he needs to precisely grasp the timing and continuously send the blowpipe along with the molten glass on it back to the kiln for reheating in order to maintain the plasticity of the glass at high temperatures.
When the glass "pancake" reached a certain size and the expected thickness, Lin Feng made a bold attempt.
He gestured for Wangcai, who had undergone some basic training, to hold the end of the blowpipe in its mouth and try to keep it steady.
He quickly picked up a flat, hardwood board that had been soaked in water and polished smooth, his eyes focused, but his movements were resolute. He pressed it quickly and gently against the half-molten glass "pancake".
With a soft "sizzle," the wooden board made contact with the scorching glass, producing a wisp of smoke and the sound of water vapor evaporating.
First attempt, failed. The edges of the glass disc cracked due to uneven pressure.
On the second attempt, the glass disc was blown too thin and shattered under the pressure of the wooden board.
On the third attempt, the temperature control was slightly off, and the wooden board stuck directly to the glass. When it was removed, a large piece of the still-unsolidified glass came off with it.
Fine beads of sweat appeared on Lin Feng's forehead, but the determination in his eyes remained unwavering.
Every failure was a profound lesson. He carefully reviewed every detail, adjusting the force of his breath, the amount of molten glass he used, the reheating time, and the technique and timing of his pressing.
Wangcai faithfully carried out the instructions. Although it did not quite understand the meaning of its master's efforts, it could clearly sense its master's almost obsessive urgency.
After failing seven or eight times in a row, and half of the glass in the crucible turning into piles of solidified waste, Lin Feng's movements and perception were honed to become increasingly sharp through countless trials and errors.
He discovered that the thickness of the glass disc had to be just right, and the timing and pressure of pressing were crucial; even the slightest difference could lead to disastrous results.
The contact with the wooden board must be swift, the removal must be decisive, and the entire process must be kept absolutely stable.
Once again, he calmly blew and swirled the glass, and a glass "pancake" with a diameter of about one foot and a relatively uniform thickness was formed again.
He gestured to Wangcai to steady the blowpipe, then picked up the wooden board that already showed signs of carbonization, held his breath, focused his gaze on a single point, and slammed it down onto the glass disc!
This time, an inexplicable intuition told him—that's it!
The wooden board made even contact with the glass surface. In the instant he quickly withdrew the board, a roughly flat glass plate, with irregular edges, an imperfectly smooth surface, and even some marks from the wooden board, stubbornly clung to the end of the blowpipe!
Although it is far from the ideal of perfection, it is indeed a piece of glass with the shape of a "plate"!
A surge of joy coursed through Lin Feng's heart, but he forced himself to suppress it, because the most challenging step, the one that would test his patience, was yet to come.
Glassware is most susceptible to damage from sudden temperature changes, as these can cause uneven thermal stress inside the glass, leading to cracking.
This glass panel, barely formed, is filled with this unseen "killing intent" inside.
These stresses must be eliminated through a slow and precise annealing process in order to truly stabilize the material and make it a usable material.
Lin Feng had already built a small, well-sealed annealing kiln next to the main kiln using stones and clay.
While melting the glass, he had already ignited a fire source in the annealing furnace to maintain a relatively high and uniform temperature inside—about five or six hundred degrees Celsius. This was the temperature he had figured out through experience over a long period of time.
He carefully used a specially made ironwood pole with a flat tray at the front end to remove the glass plate, which was still radiating an astonishing heat, from the blowpipe and let it fall steadily onto the tray covered with fine sand.
Then, with the fastest speed yet the gentlest movements, he carefully moved it into the preheated annealing furnace.
After placing it in, he immediately and carefully sealed the kiln opening with stone slabs and clay, and then began to gradually reduce the firewood at the bottom of the annealing kiln, allowing the temperature inside the kiln to drop at an extremely slow rate.
He planned to make this process last at least a whole night, or even longer, to ensure that nothing went wrong.
After doing all this, Lin Feng felt an indescribable sense of exhaustion wash over him.
He almost collapsed to the ground, his gaze fixed on the tightly closed annealing kiln opening, his heart filled with anticipation and a hint of barely perceptible unease.
Finally, after a long and agonizing wait, the temperature of the annealing furnace has been reduced to a level almost identical to that of the external environment.
With an almost reverent excitement, Lin Feng carefully moved the stone slab blocking the kiln entrance.
A ray of morning light shone gently through the opened kiln opening.
He saw several glass plates, bearing the fruits of his countless efforts, lying quietly on the fine sand.
He held his breath, reached out, and gently, tentatively picked up the first piece that had been placed in the bowl.
It feels slightly cool to the touch and has a firm texture. Success!
Although the glass plate is far from perfect—it is uneven in thickness in some places, has visible ripples on the surface and some small, incompletely escaped air bubbles, and the edges are not very regular.
But it is indeed a sturdy glass plate with considerable transparency!
Sunlight could pass through it without obstruction. Although the light was slightly strange due to refraction, its clarity far exceeded Lin Feng's initial expectations.
He took out the other glass plates one by one.
Five pieces were sent into the annealing furnace. Three pieces were successfully annealed and remained relatively intact. The other two pieces developed several minor cracks during the long annealing process due to some unpredictable and subtle stress changes. However, Lin Feng thought that perhaps after careful cutting, they could be used in smaller places and not be completely wasted.
Lin Feng raised the largest piece of glass in his hand, facing the rising sun.
Golden rays of light pierced through, casting a bright and warm patch of light on the ground behind him. He could even see the outlines of trees in the distant mountains and forests clearly through this solidified light.
"That's great...that's great!"
Lin Feng's voice was hoarse and trembling, as he gripped the glass tightly, as if he were holding the light of the entire world in his hands.
Wangcai and Meiying also sensed their master's heartfelt joy, excitedly circling around him and whimpering softly, sharing in this hard-won success.
This wooden house will finally have windows in the real sense, welcoming a brand new world full of light.
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