How to identify ancient jade?

China jade processing can be traced back to 6000 years in Yangshao and Hongshan Culture. Jade carvings such as Yulong and Yugai have been found at that time. At that time, people had not mastered the technology of metal smelting. Jade processing is mainly based on stone attack, chiseling, carving, drawing lines and grinding jade with sharp stones. The so-called "stones from other mountains can attack jade." Later, people collected or made "jade-removing sand" from hard rocks to cut jade, and used ropes, animal teeth, wooden poles, bone chips and stone tools to drill, saw, grind and shape jade materials. This is the main method of prehistoric jade processing.

It is a great progress to process jade articles with rotating weights. The original weights probably began in Liangzhu culture period. People pull the bowstring by hand (and then use the pedal) to turn the load wheel. The heavy wheel is made of stone, and different heavy wheels are made of jade sand and jade.

The thallium wheel made of copper in Shang dynasty was not strong and easy to wear itself. The groove line is shallow and wide, and the cross section is mostly semi-circular. At the end of the West and the beginning of the Spring and Autumn Period, iron and thallium are hard, so they can be made thin and pointed to improve the machining accuracy. Fine lines and deep grooves can be carved. After the wheels were made of copper and iron, iron thallium was used until the early Republic of China. From the late Republic of China to the 1970s, there were workshops in some places where iron thallium was used to remove jade sand and cut jade. This method of processing jade articles is commonly known as old workers. After the 1980s, almost all high-speed power tools and abrasives made of artificial emery were used. In this way, modern jade processing, power tools and grinding wheels are unified, which is a new job.

The difference between old workers and new workers stems from the different tools and abrasives used, as well as various phenomena and different traces caused by the speed, efficiency and accuracy of these tools. This is the starting point for judging old workers and new workers.

The working procedures of old workers (iron thallium workers) are roughly as follows: tamping stone, grinding slurry (or collecting natural sand), digging jade, digging room, laying flowers, cutting jade, grinding jade, drilling and polishing. They are characterized by manpower and iron thallium, slow rotation speed, jade sand grinding jade, and wear of materials and equipment at the same time. Old workers use manual positioning control, which has poor accuracy and large geometric error, and there will be differences in parallelism, datum plane and graphic symmetry. However, the old working medium is fine, the grinding amount is small, the machining intensity is light, the cycle is long, and the jade parts can not stand the heat. The jades carefully made by this old worker are exquisite in workmanship, well-proportioned in shape, smooth in lines, wide in excavation, soft and smooth in pressing and polished. Such an old worker is a good worker.

The new worker's working procedure is: cutting jade with a grinding wheel, peeling off the coarse grinding tool, and driving the flexible shaft with a stepless speed change motor. The chuck of the flexible shaft can be replaced with different grinding wheel weights made of artificial emery, and the highest rotation speed can reach 1000 rpm. Due to the high rotating speed and rapid grinding of emery weight, the manufacturing time is greatly reduced and the working efficiency is significantly improved. Because of this, the rough work of new workers often has traces of rapid formation. For example, high-speed dry grinding, jade watches will be hot and fuzzy. When drilling a hole and opening a window, the grinding wheel is rough and fast, and the side wall of the hole or window will be hairy after being heated. Emerald watches will have some groove marks around holes or windows, parallel burrs, and sometimes yellow burnt color will be seen.

The difference between old workers and new workers can always be seen by careful observation with a magnifying glass. The following is a comparison of their typical characteristics:

1. Lines: The old workers are slow, the lines are smooth, and there are no cracks on both sides of the lines (especially criss-crossing, reticulate and intact). The bottom of Laogonggou is frosted, and there is no obvious long strip abrasion mark. This is because jade can only be ground when iron thallium comes into contact with desquamation sand, which is quickly taken away by thallium wheel, leaving only a short grinding mark, so it is impossible to draw a long road. Old workers who don't do fine work sometimes see uneven speed and pressure of thallium wheels, resulting in potholes at the bottom of the ditch, different widths of the ditch lines and repeated weight of thallium lines. Such an old worker is a clown.

The new worker's lines are quickly shaped by high-speed grinding with grinding wheel weights. Jade cracks often appear on the edge of the line, which makes the line have serrated edges. There will be long wear marks on the groove bottom of the new I-beam, because the sand grains on the grinding wheel mound can't be arranged evenly, and there are always some sand grains protruding slightly, and the protruding sand grains will draw long stripes on the groove bottom under high-speed rotation. However, some new workers imitate the old workers, and the sand of the grinding wheel is very fine, so when processing wire, the force is small, the ditch edge is also complete, and the bottom of the ditch is smooth and flat. At this point, as long as you look at whether there is frost at the bottom of the ditch, you can identify whether it is old or new.

2. Drilling: Old workers drill jade sand, and the hole wall is frosted. If the sand is coarse, there will be groove marks, but the groove marks are irregular, and sometimes the poor discharge of jade sand will make the aperture uneven. New emery grinding tool, high-speed grinding, spiral hole wall with groove marks, straight hole.

3. Window opening: The old worker passes the steel wire saw through the borehole, then pulls the jade with the jade-removing mortar, pulls it around the window to be molded, and takes out the core window. It is characterized by marking the inner wall of the window with a wire saw, which must be vertical to the window and have a sharp edge.

New workers also drill holes first, and then use a high-speed abrasive tool to grind off the jade material in the window along the hole until the core is taken out or completely ground off. In this way, the wear marks left by the new workers on the inner wall of the window must be parallel to the window and form a 90-degree angle with the wear marks of the old workers, and the edge of the window is not sharp.

4. Hole-forming: Old workers make a hole that can't be penetrated on both sides, and slowly grind (press) it out with jade sand and thallium. Due to the large amount of cutting, the mortar is often rough, so there will be rough sanding on the inner wall of the hole.

New workers also use the top weight, but this top weight can directly grind jade, so it will leave spiral grinding marks on the cave wall.

5, eviscerate: When the old workers make small mouth workpieces such as snuff bottles, they use bay thallium and jade sand to eviscerate. Bent thallium is a steel wire, the lower end of which is bent, and when it rotates, it will form the shape of the inner cavity, which will drive the jade sand to grind the inner cavity and make it shape. This principle also applies to pulling out the bowl cavity and the ring cavity. Therefore, beautiful annular frosted marks will be left in the working hole. New workers have high drilling speed, fast grinding and tight working hours. They often use a drill bit to drill directly into the bottle hole in all directions, and then grind it flat. The inner bore is tapered, and the bore wall is thick on the top and thin on the bottom, which is very uncomfortable.

6. Pressing the ground: the old workers finely carve the ground and carefully level the ground with jade sand, regardless of working hours. However, due to manual operation, the ground can only be softened and flattened, with a large overall error and a sense of depth or slight waves; New workers have high production efficiency, tight working hours and rough working places, especially rough edges and corners; Moreover, seiko is operated by machine tools, and the ground is particularly flat and error-free.

7. Polishing: Old workers are polished evenly, soft and lovely. The glass buried in the ground for thousands of years is still bright and reflective, and few wear marks are seen. The contrast between the unpolished part and the polished part of the old workers is small, because the jade-removed sand is softer than emery and mixed with other impurities, and the rough surface left after processing is smooth. Although unpolished, the contrast is not great compared with the polished surface.

New workers polish quickly, especially rough workers, and the bending radian on the workpiece is uneven, and there are dead corners at the edges and corners. Polishing and grinding marks can be seen in some places, and there is a great contrast between the unpolished part and the polished part. Under high-speed and powerful polishing, there is excessive polishing (loss).

8. Round carving: When carving a curved surface, the old workers are delicate and have no excessive wear, while the new workers are not quick to master the grinding and the arc is not smooth, which will cause the phenomenon of ridging.

9. Coarse trench: Thallium is often used to dig coarse trenches, and the old workers will be fine if they go down to thallium. The new work has high processing speed, uneven transition, roughness and grinding marks on the inclined plane.

Not every jade article will have the above 9 points, and some features will not be typical. But by comprehensive observation, we can judge whether this item is unclear, whether it is an old worker or a new worker.

If the jade in our hands is an old jade that has been unearthed and soaked, and it is naturally aged and colored, then we generally don't have to worry about whether it is a new work. Ancient people can only process it as an old work, unless the old jade is newly made. On the other hand, if a piece of jade is a new feature, it is not necessarily a modern work. Whether it is an old jade, it has been polished, and even a newly unearthed story can be compiled. Don't believe it.

Let's talk about Lao Yu, a new worker, a new worker, Lao Yu:

There are three new works by Lao Yu. One is to repair the old jade, such as adding decorative patterns to the old jade. The second is the reorganization of old jade, such as changing the broken wall into jade yellow. Third, the old jade is newly made, using the broken old jade to transform some small jade articles, such as anal plug, nasal plug, tooth punch and so on. The purpose of Lao Yu's new work is to improve the value of jade and try to sell it at a good price. However, Lao Yu's new trade union has many clues. In addition to the above nine kinds, the first kind is to destroy Lao Yu's skin. As we all know, jade will have a waxy and calcareous shell on its surface after being buried for a long time. If you apply for a new job, the jade surface will become shiny and textured under the new job. It will be different from the original surface luster and texture. Lao Yu's new work will also destroy the color and grain of Lao Yu's piano and make it break, which is also a feature of Lao Yu's new work. After the transformation, the jade under the leather shell is exposed, and the color of the old jade seen through the leather shell is different. This is because the soaked leather shell has been worn away, and the piano color has become a castle in the air, an "isolated" piano color, and lost the "door" to enter. Lao Yu's new work is very confusing, and he will be fooled if he is not careful.

Xinyu's husband imitated Xinyu's husband. Because there are some stones and edge jade with natural patterns in the world, some are dark green and some are calcified, so some people use these stones to imitate old jade. In order not to give the cloven foot in workmanship, some windows are also pulled out by hand saws, some are finished by new workers first, and then scrubbed with jade sand, and some are carefully marked with extra-fine emery weights to slow down the speed and prevent the lines from collapsing. After it is done, it is necessary to make artificial skin, gray skin, fake soft mud and fake soil to bite all kinds of flower heads and put them out of cages to cheat people and money. In addition to recognizing jade, Xinyu Old Palace can easily find traces of new workers in drilling, trench bottom, the first hole drilled when opening the window (even if the wire saw is sawed off, half of the remaining hole will still be left), the dead corner along the bottom and the shape of the hole, thus seeing through the trick.

Now it is reported that new workers have made new progress, such as laser engraving, microwave vibration engraving, sand blasting engraving and so on, but as long as we know the old workers, then any other processing methods will not be exactly the same as the old workers. This is because ancient people and modern people can't be the same in terms of aesthetics, understanding of decoration and modeling, and the differences in tools and equipment used. Therefore, the manufactured devices will inevitably have different charm and temperament, and will also have different workmanship and technological treatment. Although some imitations are carefully imitated and disguised, as long as we look more carefully and carefully, we will always find clues, see flaws and avoid being fooled. One thing to point out is that the equipment, tools and abrasives of modern new workers will be more advanced than those of ancient times, and well-made jade articles may completely surpass Lu Zigang! It is our recognition and hope to create a brand-new contemporary jade art with advanced processing methods and modern technology!

(This article is forwarded for research and study)