Kaichi cleaned up the broken glass and took them to Im, perhaps, magic could solve the problem.

He went to his teacher's room, where Imu was drawing, and he was designing an evolution circle about charcoal. The invention of every kind of magic (array) is not a simple matter, and involves many things. The vast majority of mages have spent their entire lives in the gray robe class, and if they can have a magic of their own design passed on, it can be regarded as a success.

So Imu has been running out of time lately, so he has a lot of questions to ask, and he spends most of his time designing a magic circle that can be purified by using the principle of charcoal, and after the magic circle is designed, he can also refine magic.

After all, this is a new idea, and the purification circle using the principle of charcoal is unprecedented.

Seeing Kaichi coming over to find him, Im asked, "Is there something wrong?"

Imu looked up, and there were already a lot of bloodshot in his eyes, as if he had not slept well and woke up early. Yimu likes Jiayi's apprentice, or rather, every teacher likes this kind of student who studies hard and studies well, and it is easy to teach.

"Teacher. Garni handed his broken glass to Imu and did not speak.

Imu took it and looked at it and said in surprise, "Crystal, how is this happening?"

He picked up a piece and looked at it carefully, and said, "It wasn't crystal, this, this is glass." ”

Jia Yi was about to speak and show off, when he heard this, he was half frightened to death, could it be that there is already a glass making process?

He had looked for information when he was reading historical texts before, and it seemed that both the East and the West had a history of making glass a long time ago. It's just that the oriental one is called colored glass, also called medicinal jade, and the production process is cumbersome, so it is made as a gemstone. It's beautiful, but it's not practical. He once saw the glazed chime of the Han Dynasty in the Nanjing Museum, which did look like green jade and was opaque. Ancient glass in the West is more similar to modern glass, and it appeared much earlier and more practical. However, it was not until the end of the Middle Ages that it really began to be practical, which was equivalent to the end of the Northern Song Dynasty, and it was not until the 17th century that it got rid of the identity of luxury.

In case, in the age of magic, it is not impossible for glass to enter practical use earlier.

Jiayi comforted himself again, even if glass has entered the practical world, it is likely that it is still a luxury and ordinary people cannot afford it. Because the lord's house didn't have any glass windows and glasses.

"Kaichi, did you make this?" asked Imu curiously.

Jia Yi pretended to be relaxed and said, "Teacher, have you ever seen this, this glass? I want to see what will become when the sand is burned, and it will become like this." ”

"This glass is more abundant in the southeast, and the temple's church likes to use colorful glass embedded in the roof to attract ignorant believers. ”

Im told Kaichi that because the mage and the church did not deal with each other, it was impossible to completely cut off contact, and they also needed to communicate with each other. On the southeast coast, it connects the North Forest, the base camp of the mages, and the church-dominated East Antarctica, because of its unique geographical location, it communicates the business exchanges between the mages and the church, resulting in a relatively developed business there. Later, several small countries there combined to form a mercantile political union called the Maritime Trade and Commerce Promotion Federation.

The merchants there mastered the firing process of glass, and although the glass was relatively small, it was already usable. Most of the glass has been spent on the dome of the church, which is colorful and beautiful.

Merchants who had mastered the art of firing glass regarded it as a top secret, and all the glass artisans were sent to an isolated island to produce glass, and they were not allowed to leave it for the rest of their lives.

And the mages did not spend any effort to study the making of glass and improve the process. Because although glass and crystal look very similar, glass can't isolate magic, and holding potions or something will cause the magic power to slowly overflow and reduce the effectiveness of the medicine. Only crystals can be used to store items containing magic such as potions.

After introducing the glass, Imu asked Jiayi: "Why is your glass like this, it should be broken, right? It's all broken into small pieces." ”

"Yes, teacher, after I do it, as long as I hit it gently, it will easily burst, and I don't know what's going on. Kaichi described his predicament to Im in detail, and even some of the attempts he had made.

When Imu heard this, he said, "This is stress. ”

"Stress?" said that Kaichi seemed to have heard of this statement, and it seemed that after the parts of the precision instrument were successfully processed, they also needed to relieve the stress before they could be used. But Jiayi is not engaged in manufacturing, and he really doesn't know much about this.

"Yes, stress. The so-called stress is the force inside the object, such as an object has been deformed, temperature changes and other external forces, which produce an interactive internal force between the parts of the object to resist the action of this external factor, and try to restore the object from the deformed position to the position before the deformation. If there is still stress remaining inside the object after the external force is removed, it will have an impact on the object, and when the stress is greater than the zero cut-off point, the object will be damaged, which is called internal stress. ”

Seeing that Jia Yi still didn't understand very well, he said: "For example, if you bend a piece of iron hard, after the external force is removed, it will become straight, which is stress; and the wood chips cut from the tree will curl by themselves, which is also stress; some ripe melons and fruits will explode when you touch it lightly, and this is still stress." The glass you make is because of the high temperature, which causes a lot of internal stress to be left inside, and a slight impact will exceed the stress limit, resulting in bursting. Just stress relief is fine. ”

"How do you get rid of that?"

"There are many ways to relieve stress, the simplest is to put it there, and after a few decades, the stress will slowly eliminate itself. ”

Jia Yi's eyes widened instantly: "Decades?"

"Listen to me! That's just the easiest way, there are other ways. The most common method is heat treatment. Hold it at a certain temperature for a certain amount of time, and then cool it down to relieve the stress. ”

Hearing this, Jia Yi breathed a sigh of relief, and heard Yimu say again: "There are some other methods that are not commonly used, such as beating, shaking, and so on. And, of course, the most convenient magic. Mage Straths systematically summarized stress and invented several spells about stress, including strain relief. ”

"So, teacher, can you help me relieve my stress?" asked Kaichi.

Im smiled and said, "Unfortunately, I won't." ”

"Huh?" Kaichi's disappointment was palpable, how could such an important magic not be learned.

Seeing that Kaichi was so disappointed, Yimu smiled and said, "This kind of magic is not used by anyone else except for blacksmithing or alchemy, so I didn't learn it." I was curious and learned the art of stress, which is a stress-increasing magic that can add stress to an item and make it more susceptible to damage. ”

Kaichi looked at Imu, this magic seems to be practical, but he can't use it, does it add stress to the glass and make it shatter more completely?

When I was lost, I heard Imu say, "But, with this magic, I can feel the stress inside the object." We can use heat treatment to relieve the stress inside the glass. When the magic senses that the stress starts to resolve, maintain it at this temperature, wait until the stress is all gone, and then cool down, so that it should be fine. ”