Early the next morning, Li Su got up early. Wash and change clothes under the service of grass, and read a book in the house.

When he had rested for about a while, Cao'er brought a plate of morning food, and told him by the way that the best silversmith in the business had been recruited, and that he could go to see the mirror mill after eating.

The morning snack is a bowl of hot and sour soup with dogwood fish fillet, in addition to the fish, there are also Chinese cabbage, and some mutton fat to taste—which can be roughly understood as the sauerkraut fish noodles of later generations.

Looking at this, Li Su also wanted to cry: the food in the small shop for more than 20 yuan in later generations has to be used as a breakfast for guests by a super-rich man like the Mi family, whether it is dogwood or peppercorns, it is an expensive spice.

The queen's bedroom in Weiyang Palace is called "pepper room" because when the wall is painted white, the putty is mixed with pepper powder, which can repel insects and remove the smell, and it is very upper-class at first glance.

Next to the noodle soup, there are several lacquered plates with a variety of fish sauces such as pure white and pink.

The fish is cut as thin as a cicada's wings, and guests who like to eat fish can soak it in the noodle soup kept warm by mutton fat, and it will be cooked quickly; You can also eat it raw, with a dipping sauce next to it.

Li Su only recognized the sea bream, and ate a plate of raw food directly.

Fortunately, this is a harbor county, otherwise with the preservation technology of the late Han Dynasty, if you go a little inland, you won't be able to eat such fresh fish.

Back in the Han Dynasty, no matter where you go, you should recognize the local specialties to eat.

Cherish every time, change places and it will be gone.

But despite this, Li Su only eats sea bream, and the others are either cooked or simply left untouched - because when he was eating, Cao'er inadvertently said something to him that showed his intentions, which made him tremble:

"When Guangling Chen County Ling came to our house as a guest, he liked our fish, and he was full of praise for each of them."

When he heard this, Li Su almost dropped his chopsticks on the table.

Chen Deng ate fish and died of eating it, and even Hua Tuo couldn't be saved.

……

After eating the "minced top-quality sashimi", Li Su wiped his mouth, and under the guidance of Cao'er, he came to a craftsman's room in Fuzhong.

The furnishings in the house are not gorgeous, but there are a lot of luxury goods and various tools, and at first glance this room is used to renovate those precious things.

An old silversmith who looked to be fifty years old, with an apprentice, was repairing and renovating there, and there was a steward overseer from Mifu, apparently to prevent the craftsman from stealing the raw materials used for the repair.

The repair materials used in this kind of work are gold, silver and gemstones, so you have to be careful.

When Li Su came in, the steward and silversmith also stopped and saluted him, and Li Su said that it was okay and motioned for them to continue.

Then, Li Su saw the young and strong apprentice of the old silversmith, holding two bronze mirrors with slightly greenish sides, sprinkled with some water on the surface, and grinding each other violently, the lower one was fixed with a clamp similar to a whetstone trough, and the cloth towel was padded, and the upper one was in his hand.

"It seems that the polishing of copper mirrors in this era is to rub each other directly on two mirrors, but in this case, there will still be scratches or slight wire drawing traces in the end, which will not be too smooth." Li Su saw it in his eyes and pondered in his heart.

While thinking, I took the polished copper mirror and verified it, and sure enough, it was so.

This roughness is similar to that of the later generations of brushed aluminum mold goods, and it is estimated that it is used by the maid in the house, so it is so simple to deal with.

Li Su declared in his heart that this technology had no reference and improvement value, and then looked back at the operation of the old silversmith.

The old silversmith was much more stable than his apprentice, he first took a relatively fine whetstone, and sharpened it for a while, and the blackened silver oxide protective film was worn off, revealing the bright white and reflective sterling silver inside, but the silver surface at this time had been destroyed to a little rough.

He then took a handful of something that looked delicate and like flour, dipped it in a little water, wiped it on the surface of the mirror, and then skillfully wiped it along the surface of the silver mirror with a delicate piece of silk.

After a while, at least a few coins of silver powder had been filed off the ground, and the silver surface was finally smooth enough to faintly see the human face.

During the whole process, the thickness of the silver mirror was also visibly thinner by half a minute.

The steward of the Mi family carefully took a silk rag—he didn't even dare to use a broom—and roughly wiped the floor of the bluestone slab, smearing the silver powder on the ground into a jar to be taken back for smelting. However, because the silver powder is too fine and somewhat oxidized, the fire consumption is estimated to be very high.

Seeing this step, Li Su already roughly understood the core competitiveness of the mirror grinding process - the key is the pinch of abrasive as delicate as flour.

Although he was a liberal arts student in his previous life, he was also a scholar. Xueba, most of them have a high degree of myopia, he himself is 1200 degrees myopia, and he can't even use contact lenses, so he can only use glasses.

In order not to be as thick as the bottom of the wine bottle, the lenses of such a height can only be made ultra-thin, and then they are very expensive. So much so that when he was in college, because he didn't have a job income, he was very distressed every time his glasses were scratched.

So he also searched Baidu for "what to do if the spectacle lens is scratched", and Du Niang told him: As long as the spectacle lens is not coated, you can use a little toothpaste and water, get it evenly on the lens, and then wipe it vigorously with a glasses cloth.

He tried it and found that the lens scratches were really repaired, although the prescription was a little inaccurate, and the coating was worn off, but it finally extended the service life of the poor Xueba's glasses by several percent.

Because he was concerned about his personal interests, he also specially studied this matter in Baidu, and later learned that it was the toothpaste, a calcium carbonate powder, that played a grinding role.

He still remembers the relevant data found on the Internet: the grinding accuracy of commonly used sandpaper is only 100~200, and the thinnest whetstone is about 400. The abrasives with a precision of more than 1500 are basically like toothpaste, shoe polish, and facial cleanser.

The abrasive used by the old silversmith in front of him is estimated to be limestone powder, but the Han Dynasty people can't polish the stone powder to a finer level. From the perspective of later generations, it is estimated that the grinding accuracy is 500~600 at most, no wonder the silver mirror is not very clear.

Seeing this, Li Su already roughly knew what he had to do: he had to find a way to make a "toothpaste".

Of course, this toothpaste is not for brushing teeth, so there is no need for fragrances, detergents...... these ingredients.

At the heart of this is the finest possible calcium carbonate abrasive, plus lubricants and adhesives, these three materials are made into "toothpaste", which can grind the clearest and most durable silver mirror in the world today.

If you really don't have lubricant, you can sprinkle water directly like the old silversmith, but it is better to have a clear clear oil. There was no Vaseline in this era, but the sharpening oil and phytic acid oil used by the ancients to maintain swords could also be used improvised.

The role of the adhesive is to ensure that the abrasive particles are evenly dispersed in the paste and do not agglomerate, otherwise it will still scratch the mirror. The material of this kind of thing, Li Su also saw on the ingredient list of facial cleanser in later generations, mainly sodium metasilicate - to put it mildly, it is the "seaweed mud" and "volcanic mud" and the like that are advertised in facial cleanser advertisements.

As a harbor county, volcanic mud is definitely not available, but there is a lot of diatom mud.

During the meal in the past two days, Li Su ate kelp and seaweed more than once. Although it is not farmed, but the wild goods picked back by fishermen, it is still very easy to find a few fishermen to dig a pile of algae residue and come back to grind, filter and clarify.

Li Su wanted to understand this, so he walked away, and pretended to be unintentional and left a few words, saying that he had seen a better-polished silver mirror in the Zhen family's business in Jizhou.

Of course, the old silversmith was not convinced, but the craftsman had a humble social status and did not dare to refute Li Su in person, so he let Li Su go.

This can also be regarded as Li Su's foreshadowing for coming up with a better silver mirror in the future.

……

After leaving the silversmith's place, it was not yet noon, and there was still half a day to go, Li Su simply found a few of his own soldiers and went out to buy some things—not all of them were materials necessary to make abrasives, and many of them were smoke bombs for cover, and in the end they were not used at all.

However, these miscellaneous materials are not expensive, so it is not a pity to waste them.

And it's also a godsend - this time, the core raw material for experiments, quicklime, does not need to be bought now. Because when passing by Pengcheng a few days ago, Guan Yu bought a lot of quicklime for pickling people's heads, and there were a few packs that were not used up and put in his luggage.

Therefore, Li Su's secrecy work can be described as seamless, even if someone notices that he went out to buy goods before he took out the high-end silver mirror in the future, he will not be able to find the core material of quicklime.

In addition, Li Su also let his soldiers occupy a deserted ancestral hall outside the city, because he didn't want to conduct scientific experiments in Mi Zhu's house. (Today, there are no Buddhist temples or Taoist temples in the Huaiyang area.) The shrines are all dedicated to the Taiyi God. The Buddhist temple in Huaiyang was later spread by the Danyang warlord Zhenrong)

It was in this preparation process that Li Su made another discovery - he originally wanted to buy knife grinding oil as grinding lubricating oil, but later found that the blacksmiths in the late Han Dynasty had not yet used the concept of "sharpening oil".

In other words, today's iron armor and iron weapons are not treated with grease and rust, and they all hope that the inner layer will no longer be corroded after the oxide or sulfide protective layer is formed on the surface, just like in the Bronze Weapon Age. (Blacksmiths use a certain amount of grease when forging and quenching, but no one uses the sharpening and maintenance of knives after leaving the factory.) ）

It is no wonder that the vast majority of today's iron armor is "Xuanjia", because the black rust and dense oxide layer can protect the iron inside. And the shiny armor was more used as a guard of honor.

The blades of the horse slashing sword and the ring head sword do not have the shiny smooth blades of the swords of later generations, and the colors are quite dull.

But fortunately, Li Su finally found a barely usable phytic acid oil - anyway, as long as he is an acidic vegetable oil, it has a certain antioxidant effect, and his eyes are already clear and transparent, so he can use it to grind and protect the silver mirror.

This incident also reminded Li Su that in the future, he can buy a little more phytic acid oil that meets this kind of conditions by the way, and use it to smear weapons and armor for the army, although it cannot improve the combat effectiveness of the equipment, but it can definitely improve the durability of the equipment a lot.

The weapons of other warlords will rot into slag in seven or eight years at most, and the armor of Li Su's troops may be able to double the standby time.

After working for a long time, after the two things of seaweed mud and phytic acid grinding oil after filtering and clearing,

Li Su is ready to personally deal with the last and most core material - a sufficiently fine calcium carbonate grinding base.

"I didn't expect that I would have the opportunity to use the first lesson of the junior high school chemistry laboratory class. I hope the chemistry textbook doesn't lie to me. Before starting, Li Su prayed silently in his heart, looking forward to all the best.