China's ancient copper mirror is how to do

Copper mirror casting production process

The so-called copper mirror casting production process, refers to the pure red copper and tin, or lead or zinc, through a strict ratio, smelting and melting, and then poured into the mold, after cooling, remove the blanks, and then finally mechanical processing, the surface coated with tin and mercury, to become a daily necessities can be light capacity of the process.

The production of copper mirrors to carry out many procedures, and each process has strict standards.

If a defect occurs in one of the processes, it will affect the quality of the mirror, or even produce defective products and bring losses.

In the process of more than four thousand years of history of copper mirror, the Warring States, the two Han, Sui and Tang dynasty copper mirror production is the most exquisite, is the product of the social and economic prosperity at that time, for the collector diligently pursue.

After the Song Dynasty, the lack of fine products, the historical reasons should be related to the loss of some of the key casting process.

Although the Ming Song Yingxing "Tian Gong Kaifu" book has introduced, but not in detail, difficult to grasp, and is a matter of Song later.

In recent years, with the collection of hot warming, the depth of the study of ancient copper mirror, and gradually on the ancient copper mirror casting production process has a comprehensive scientific analysis and understanding.

As a collection of copper mirror enthusiasts must have a comprehensive understanding of the casting process of copper mirror, master the knowledge of the whole process of production of copper mirrors, with theory to guide practice.

Under the support of perseverance, in order to slowly enter the collection of good, so as to realize the bronze mirror in kind, both theoretically and practically, on the identification, dating, restoration, identification of forgeries, are able to have a correct judgment.

(a) mining and smelting:

Bronze is red copper and tin, lead and other metal alloys.

The ground can be collected very little natural copper, copper mirror casting a large number of must rely on large-scale mining and smelting of copper ore.

The development of copper mining resources in China was the material basis for the development of the casting industry in the Shang Dynasty.

China's bronze remains in large quantities, indicating that the ancient copper mining and smelting has a considerable scale.

Because the mining remains buried deep underground, not easy to be found, so far, archaeologists have found large and relatively large mining and metallurgical sites are only a few: such as the Daye Copper Green Mountain mining and metallurgical sites in Hubei Province; Liaoning Province, Linxi County, Dajing ancient copper mine site; Hubei Province, Mayang ancient mine site; Anhui Tongling copper mine site and so on.

(B) the various periods of copper mirror alloy composition:

"Kaogongji" is an important scientific and technological works in the pre-Qin ancient books, it is the end of the Spring and Autumn period of the Qi people to record the official book of handicraft technology.

It is the earliest record in China and the world on the alloy ratio of bronze mirrors and other artifacts.

Bronze is the earliest alloy of metals.

Humans entered the Bronze Age from the Stone Age, about 5000 years ago.

The first people began to master the art of making alloys.

The use of two or more metals, through high temperature to make it fused together, made into another metal, which has new physical and chemical properties, this is the alloy.

Alloy in the casting is a metal re-creation, bronze is the first alloy.

Bronze as an alloy, compared with pure copper, it has the advantages of high hardness, good luster, can emit blue light, can light capacity, as well as good corrosion resistance.

Ancient Chinese tin bronze often contains a small amount of lead, so that the copper liquid in the casting of smooth performance, not easy to block, but the lead molecules only dissolved in the copper, can only be uniformly distributed in the copper for the drop floating suspension.

The melting point of red copper is 1084.5 ℃, if you add 15% of the lead, the melting point down to 960 ℃, if you add 25% of the tin, the melting point is 810 ℃.

However, the significance of adding lead or tin is not only to lower the melting point, but more importantly, the physical and chemical properties of the alloy are greatly improved.

In the Western Zhou Dynasty, 3000 years ago, our ancestors have skillfully mastered the complex alloy manufacturing technology, and create modern people breathtaking, exquisite bronze art.

Such as the majestic heavy bronze tripod, delicate and clear cloud mirror, the sharp Wu Fuzhai spear and so on.

In this regard, there are a lot of records in the Zhou Rites - Kaogongji, which was written in the Spring and Autumn and Warring States periods.

The Zhou Dynasty had a winter official, Sikong, who was in charge of all industrial matters, responsible for "building cities and towns, constructing capitals, and making vehicles and equipment".

Specifically in terms of metallurgy and casting, there was a very fine industrial division of labor among the hundreds of workers, that is, "the workers who attacked the gold, Chiku's executive lower qi, Ye's executive upper qi, Teal's for the sound,

the amount of the Duan's for the spade, Peach's for the blade.

"Clearly by professional craftsmen specializing in the manufacture of musical instruments, measuring instruments, agricultural tools and knives.

This phenomenon, the Han Dynasty, Zheng Sinon explained: "It is said that a person's, the official has the world of work, if the family has the world of work, to the name of the official also.

"It can be seen, in the Zhou Dynasty, metallurgical casting industry has become an important socio-economic industries, and the historical formation of a special manufacturing a certain type of artifacts of the family, and because of the hereditary and become the name of the official, this is one.

Secondly, due to the accumulation of practical experience, the pioneers were able to extract gold (i.e., red copper), lead, tin, zinc and other metals from different ores, and understand the physical and chemical properties of different metals, and on this basis, according to their own wishes, according to the requirements of the special purpose of different objects, to create a different type of alloy.

"The theory of six Qi" is a theoretical summary of alloy manufacturing.

"Zhou Li - Kaogong Ji" records: "gold has Qi: six points of its gold and tin in one, called the bell tripod of Qi.

Five points of its gold and tin in one, called the axe catty of Qi.

Four minutes of gold and tin in one, called the Golgotha of the Qi.

Three quarters of the gold and tin in one, called the big edge of the Qi.

Five minutes of gold and two seconds of tin is the same as a kill vector.

Half of the gold and half of the tin, which is called the Qi of the flint.

"This clearly tells us that the craftsmen at the time not only know the higher the tin content of bronze, the harder the principle of texture, but also grasp the hardness and toughness, brightness in different parts of the tool in their own special requirements, according to the needs of the production.

Such as the use of composite technology to manufacture the sword, with a lower tin content of bronze for the sword spine, with a high tin content of bronze for the blade, so that the sword, the blade is sharp, the sword body is tough, lethal and durable.

Specifically in terms of bronze mirrors, brightness is an important feature, half copper and half tin, can make the finish just right.

Therefore, the sages concluded that "half of the gold and tin" is the most appropriate ratio of dosage for the manufacture of flint.

But the casting of copper mirrors in various eras, due to the influence of various factors, it is different metal ratios, processing methods are also different, so copper mirrors to break the generation, mainly with the help of advanced modern scientific instruments for testing.

For the exact generation of copper mirror, if we master the knowledge of the metal ratio of the period, combined with other aspects of the characteristics of the mirror, you can also make accurate judgments.

The ratio of copper to tin in the bronze mirrors of the Qijia culture is 1:0.096.

The Shang and Zhou mirrors have a slightly higher tin content, but the texture is far from the same as the bronze ceremonial objects of the same period, and there is a lack of necessary antirust treatment of the mirror surface.

Warring States bronze mirrors in copper, tin, lead ratio has been more stable, most of the copper in the 68% up and down fluctuations, as much as 74.8%, less than 56.6% or more, but the proportion of tin is generally in about 20%.

In addition, the proportion of lead in 0.45% -3%.

The warring states mirror has a kind of surface black transparent like coated with a thick layer of black lacquer, known as the "black lacquer ancient", this kind of mirror is well preserved, especially its anti-rust technology makes modern people marveled, which is directly related to the metal ratio of the mirror production at that time.

Han mirror alloy ratio is more stable, copper accounted for about 60-70%, tin accounted for 20-24%, lead accounted for about 4-6% of the ratio of the most common.

Han mirror preserved a little better mirror can still reflect, some of the best can also reflect the light of the greenish-brown.

Wei Jin and North and South Dynasties copper mirror alloy ratio is not stable, easier to rust, color to black and brown mostly.

Tang mirrors, especially in the Sheng Tang period of mirrors, silver-white, its metal composition, roughly average 69% copper, tin 25%, lead 5%, the ratio is more stable.

In the Tang Dynasty, has been used to the mirror to add a trace or a certain amount of silver in the new technology, so that the typical Sheng Tang period copper mirror silver-white light, very few patina, it seems to be not bronze casting, giving a person heavy, rich feeling, coupled with colorful decorations, rich in content, it is a rare work of art.

Ming "Tian Gong Kaifu" described: "Tang Kaiyuan Palace mirror all silver and copper equal parts casting, the number of silver per mouth value of both this reason.

Cinnabar spots are the essence of gold and silver found ......, Tang mirror, Xuan furnace are the court of the world.

"Tang mirror precious, because silver and expensive.

Song, Xixia, Liao, Jin, Yuan copper mirror, the alloy composition has changed, the amount of tin is only about 10%, the amount of lead has increased to more than 8%, up to 23.7%, much higher than the average of Han and Tang mirrors 5% of the number of zinc content has increased, up to 8%, so the period of the copper mirror is brass-colored, generally covered with patina.

Although the form is thinner, but because of the lead content, the reverse is heavier than the Han mirror.

The Ming Dynasty is China's ancient copper industry is more developed a stage, copper mining industry flourished, when smelting copper and its alloy technology, the main achievements are three: one is the fire method of refining copper technology has further improved; two is the direct use of zinc metal formulated brass; three is the manufacture of Xuande furnace, which in the alloy formulated to reach a new height.

Copper-zinc alloys are generally yellow, hence the name brass.

Copper-zinc alloy color and zinc content is: about 10% zinc red with yellow, about 15% yellow with red, about 25% yellow, about 30% dark yellow.

Ming and Qing Dynasty bronze mirrors are mostly yellow, the alloy ratio is 70-75% copper, zinc 25-30%.

Because of the better fluidity of brass, is conducive to improving the casting performance of the alloy.

(C) modeling ceramic model, stone model and clay model production:

Academics are known to have mirror model unearthed, about the end of the Qing Dynasty after the event, from the reports and records, these mirrors model seen in the late Spring and Autumn period, more than the period of the Warring States period to the Western Han Dynasty, counting about more than 30 pieces.

1, the production of the mirror model: the basic components of the production of pottery model is clay and fine sand.

But the pottery mold and pottery model in casting bronze mirrors play different roles, the former determines the shape of the object, while the latter needs to withstand the impact of thousands of degrees of high temperature copper, and in which to cool.

Therefore, in addition to high-temperature ceramic Fan, but also have good mechanical strength, withstand the liquid pouring wash and not damaged, but also have a certain degree of permeability.

Because the copper infusion, will produce varying degrees of gas in the Fan, most of these gases through the gate and venting Fan outside, a small amount of the need to Fan through the pores penetrate out to ensure that the casting of artifacts in the appearance of the casting defects do not see the pores.

Therefore, the production of pottery model of the clay must be very fine, in both the ability to clearly reflect the bronze mirror on the inscription and pattern at the same time, but also to have a good absorption.

To achieve excellent heat resistance and good mechanical strength, the clay used to make the model must be carefully washed.

The purpose of washing on the one hand is to classify the mud according to the particle size, on the other hand, the mud contains calcium carbonate, sulfate and other organic matter dissolved in water to reduce the harm of such salts, otherwise it will result in reducing the refractoriness, sintering temperature and increase the gas.

The model was first made with coarse "real earth" made of the prototype of the model, and then add the finer "real earth", "modeling real earth", and to the surface of the model, and then add the very fine "muscle real earth". Then we add the finer "medium clay", "modeling clay", and then on the face of the model, we add the very fine "muscular clay".

To make a mirror with a diameter of about 25 centimeters, the thickness of the fan needs to be about 12 centimeters, of which the layer of "coarse real clay" is about 8 centimeters thick, and the "muscular real clay" is the thinnest, only about 0.1 centimeters.

The advantage of this layered material method is to ensure the production of the casting of the various performance requirements, but also to save the finer quality "real earth".

"Tian Gong Kaifu" pointed out: "Where the casting of mirrors, molds with gray sand, copper with tin and, do not use Japanese lead.

"Japanese lead, that is, zinc, on the quality of copper mirrors have an impact, so can not use.

The gray sand is made of rice husk ash and other permeable and heat-retaining materials, and very fine particles of fine sand and become.

This material is suitable for mirror mold.

The stone model is now recorded and reported in the Tonghua Han Dynasty Bo Bureau four gods stone mirror model.

Fan body in the shape of a dipper, Fan diameter

about 20.5 centimeters, there is a sprue, under the width of 5.3 centimeters

meters, Fan surface graphics clear.

Inside the square of the seat, there are

twelve geomantic branches inscriptions, and the theme is decorated with four gods and rule symbols

number.

Outside the main pattern area, there is a one-week inscription band: "Shangfang made the mirror (see Figures 1-18)

It is really great that there are immortals who do not know how to grow old, who are thirsty and drink from the jade spring, who are hungry and

eat jujubes, who float in the world, who travel to the four seas, and who live as long as a golden stone for the protection of the country.

"35 words.

The Shanghai Museum also has a piece of talcum "Mirror Fan" (see Figure 1-18).

In the stone model, some can be used to cast about, such as "Tonghua stone model".

Some may be used to make the model of the negative mold, such as the "Shanghai stone model", which has the advantage of being able to withstand high temperatures and can be used many times over and over again, the line pattern is particularly special, showing the elegance, but the excavation of the object is small, in-depth study is needed.

Stone model cast mirror process when some similar to the mud model, but there are some differences, the main difference is that the model for the stone material carved directly, is a semi-permanent type.

The advantages of mud casting mirror is: modeling easier, and can produce a lot of fine as hair, no loss of fiber, the shape of the mirror back to the pattern, especially the production of large mirrors, especially convenient to make the device, the disadvantage is that usually a model can only be used once, can not be mass-produced.

The above is the mirror model unearthed and recorded in the general situation, there is significant value of the pottery model and stone model, most of the Warring States period to the Western Han Dynasty, mainly out of today's Hebei, Shandong, Shanxi, Shaanxi, Jilin and other northern provinces and regions, the South has not been seen so far, about the humidity of its land, the pottery model is fragile things related.

(D) the pottery model of the turnover:

All general bronze molding, are required to make the mold, after the production of the model.

The "mold" can be carved from wood, clay, can also be made of clay.

If the shape of the object is relatively simple, fewer products required, the "mold" can be used directly to make the model, if the shape of the object is more complex, the pattern is more elaborate, the need for it to be many times; or the need for a larger number of products, the ancestors of the mold need to be preserved for a long time to standby, it is necessary to "ancestors of the mold" (one time Yangmu). "(a Yang mold) to make "a negative mold", and then "a negative mold" to make "a second negative mold", and then "a second negative mold". "Second negative mold" to make the model.

The modification of the pattern pattern, usually preferred in the Yang mold, for high-relief patterns, can be stacked, pressed, carved, etc., in the clay Yang mold made.

The mirror cast by the official workshop, are based on the court to provide a standard mirror mold to produce.

The mature technology of bronze mirrors has been used in China for more than 2,000 years, and the patterns and shapes of the bronze mirrors of all generations are different, and the need for the product is not the same, so its turnover of ceramic models is also very different.

The study that our ancient copper mirror pottery model of the turnover is commonly used whole model whole mold reproduction, which should be our country's ancient mirror model production using the most common traditional methods.

The production of mirror back model: the practice is first made of wood, ceramic or metal, etc., the entire mirror back pattern of the mold, and then in a modeling frame with the tamping method of reproduction, only one operation can get a complete mirror back model.

This is actually a whole model whole mold reproduction.

"Ramming method" in the ancient metal casting process, has a very important significance, many copper and iron casting model is made using this method, otherwise, it will be very difficult to obtain a clear angle and pattern, that is, in modern times, some places are still in the application.

In addition, there is a whole model sub-model reproduction, sub-model sub-model reproduction and other methods.

The production of face model: the production of face model and back modeling materials should be generally the same, modeling methods are similar.

But the face of the model has its own requirements, that is, the copper liquid contact with the surface layer and support the surface layer of the thick matrix layer of different requirements.

The surface layer of terra cotta is dense, oozing with even fine sand, some of which is about 0.5 centimeters thick.

In addition to the same base layer mixed with fine sand, but also contains a wealth of holes, mainly in the soil mixed with chopped plant stems and leaves and straw and other grasses, so that when drying will not be cracked deformation, easy to cast out of gas.

(E) the basic copper mirror casting (process) operation:

1, top casting method:

China's ancient metal casting of the traditional craft is generally mainly mud, stone type also occupies a certain proportion.

Fan piece after roasting, cooled, can be combined with the model casting.

Before casting, the molds need to be preheated to prevent scrap.

The pouring temperature should not be too high, which not only reduces the metal suction and other disadvantages, but also avoids sintering on the surface of the model, to ensure smooth de-vanning and mirror quality.

Generally speaking, the inner gate is designed so that it cannot be poured.

Here are a few points worth noting:

(1) because of tin bronze dendritic crystals are very developed, the dendritic crystals between the last condensation of the small pool of liquid and no liquid metal to fill the casting in the solid state contraction is often cracked, so the casting process to avoid the metal within the self-tension, otherwise it is easy to crack.

(2) because of the condensation of tin bronze shrinkage is mainly manifested as a dispersive contraction, loose tendency is very large, so the design of the mirror, should try to take into account this factor, to avoid a large number of loose appear in the mirror.

(3) Fan and the core should be burned through, to avoid re-absorption, especially the button core, otherwise it will greatly affect the clarity of the back pattern.

Loose organization and core gas in the physical collection of ancient bronze mirrors, can often be seen.

From the shape of the existing mirror model, China's ancient copper mirror casting is mainly used in the top casting method (Figure 1-19).

A set of Fan (i.e., a piece of face Fan, a piece of back Fan) to form a casting system, each set of Fan can be individually cast, can also be stacked together.

The advantages of top-type casting are: the casting process is relatively simple, thus reducing the production workload and metal loss, the disadvantage is easy to cause metal splash.

2, lens special casting method:

Special casting method is mainly used for casting double-layer lens.

The mirror and the mirror back by two different compositions of the alloy composite embedded casting, usually the mirror back part embedded in the mirror part, that is, "mirror" package "mirror back".

Double-layer engraved mirrors were first seen in the late Spring and Autumn period, the middle and late Warring States period and the early Western Han Dynasty is still in use, until the Tang, Song and Yuan dynasties.

The back of the two parts of the metal is generally embedded better, rarely seen separated, in general, these mirrors should be the first pour mirror back, before pouring the mirror surface, metal condensation, and the mirror part of the mirror together with the mirror rim will also produce a clamping force, thus strengthening the two parts of the metal embedded.

3, clamp mirror special casting method:

China's ancient literature, on the clamp mirror has detailed records.

The folder mirror has the following characteristics: 1, the mirror and mirror back into two layers, and hollow.

2, the "front part" is thin, the same as ordinary mirrors, the "back" can also have a pattern raised.

3. There is no welding.

4. The sound is cold and far away.

Regarding the material of the clip mirror, the same high tin bronze, because only clear high tin bronze pattern, can achieve this effect.

Folder mirror molding process is more complex, not cast, not welded, is the use of a similar to the aforementioned double-layer carving pattern mirror, but not exactly the same special method of processing.

The main points of the process is: 1, the first cast into the "mirror part" and "mirror back part", and "mirror part" to be convex back a circular back to the edge, so that it can finally clamped to the mirror. So that the last can clamp the "mirror back"; 2, will cast a good "mirror back", "mirror" two parts of the metal for a quenching treatment; 3, the The "mirror part" heated to the β-phase region, that is, slightly higher than the range of 586 ° C, heat preservation while hot to make it strong with the "mirror back part" of the set, wait for cold, the two parts of the metal will be tightly bonded together; 4, with the tin amalgam to the joints smoothed and lightened, to the The seam is covered.

"Mirror" and "mirror back" two parts of the size must be very accurate, can not lose the slightest, the joint surface must be clean and clean, shall not leave any oxides, volatile substances.

"Sandwich cavity" size to choose the right, the set of fire should be appropriate, otherwise it will be difficult to achieve a long time without separating the effect.

Sandwich mirror is difficult to obtain, it seems that the main reason is difficult to make.

4, copper mirror heat treatment technology:

High tin bronze is both hard and brittle, in order to improve the processing and use of copper mirror performance, the Warring States, the Han and Tang dynasties, people often carry out some of its quenching and tempering, this operation is about casting after molding, and a little bit of simple cleanup, began to proceed.

From the modern technical principle, cast high tin bronze before quenching, the nature of hard and brittle.

After quenching, its plasticity is good, so that the strength of the material, plasticity has improved significantly, but the hardness has decreased, tempering temperature is lower, the hardness is back up, tempering temperature increases, the hardness is back down.

This mainly refers to the strength.

China's ancient bronze mirror quenching, about the invention of the Spring and Autumn and Warring States period, from the Warring States to the Han and Tang dynasties used more commonly.

From the literature and modern technical principles, the ancient mirror quenching, tempering technical effect of about three aspects: 1, strength and plasticity increased, thus improving its cutting performance, tempering temperature a little higher with the same reason; 2, because of the strength and plasticity of the improvement, it reduces the chances of damage to the mirror to extend the life of the use of the mirror; 3, tempered, the color is close to the greenish-gray, and the "green near white". "Green near white" is suitable for mirrors.

Now see the general warring states, Han and Tang dynasty mirror fracture are white as silver, when this is related.

It can be seen that after the quenching of the bronze mirror both preserved the tin state, tin bronze some of the original advantages, but also improve the processing performance, prolonging the life of the process, is a quite reasonable, scientific process.

Bronze quenching is an outstanding achievement of China's ancient metal technology, it is used so early, so wide, in the rest of the ancient world is rarely seen.