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The Terracotta Warriors
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The army of China's mighty creator buried for more than 2,000 years.  What secrets do they hold?

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Pit 1 of the Terracotta Warriors, sorry for the bluriness of the photo, I was kind of excited.

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Pit 2. Notice the thatched roofs in the background, and still yet the broken warriors.

A Background.

The Terracotta Warriors considered the eighth wonder of the world, are the largest pottery group of figurines ever found in China. They are the army meant to protect the emperor in death. The emperor made many enemies in life so its no surprise that he needs an army of an estimated 8,000 to protect him. One of the emperors plans for the afterlife that he began at the tender age of thirteen when he descended the throne after his father died prematurely. They cover a total area of 20,000 square meters in five separate pits, three of them actually containing warriors.

The first pit (the biggest of the three) was discovered in 1974 by a farmer who was in the process of digging a well. It contains 6,000 of the figures. Today it is housed in a huge dome-like structure to protect it from the elements. As well as pits two and three. Pit two is considerably smaller and pit three follows suit as it is the command center of the terracotta army. Found along with the warriors were two bronze chariots depicting the emperor traveling into the here-after.

Each warrior has a different face not repeated in any other, each with its very own expression. All are life-sized, bigger than life-sized in fact, and each one painted with the imperial colors. Most wouldn't know that though because the ones that they have seen and have come to know are colorless, when in fact they started out as brilliantly colored molds of clay that depicted an ancient time.

 

The Terracotta Treatment.

When the warriors were unearthed and examined it was noticed that the way in which they were finished was considered by our modern standards to be high art, because the statues had been painted after firing. Its considered to be "cold painting", a method that did not use a glaze.

The priming layer of the terracotta warriors is of a natural product East Asian lacquer that can be procured by injuring the bark of a lacquer tree and collecting the sap. It turns black during the hardening process. It is very precious and quite a luxury for the warriors having that applied to their outer coats, which would be quite characteristic of the emperor, and then considering the amount that would have been needed for the 8,000 individual figurines.

The lacquer was applied in two thin layers, and thick layers of natural and artificial pigments were added, with what could have been a gum or animal glue, to the top, making aqueous binding.

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Hydroxyethyl methacrylate.

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Pit 1. Notice the broken one in the back. Many were found in pieces due to a peasant rebellion.

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Pit 3, the command center of the clay army.

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The most common form of terracotta use we know.

The Terracotta Paint Reacting With The Atmosphere.

When the warriors were unearthed and examined it was noticed that the way in which they were finished was considered by our modern standards to be high art, because the statues had been painted after firing. Its considered to be "cold painting", a method that did not use a glaze.

The priming layer of the terracotta warriors is of a natural product East Asian lacquer that can be procured by injuring the bark of a lacquer tree and collecting the sap. It turns black during the hardening process. It is very precious and quite a luxury for the warriors having that applied to their outer coats, which would be quite characteristic of the emperor, and then considering the amount that would have been needed for the 8,000 individual figurines.

The lacquer was applied in two thin layers, and thick layers of natural and artificial pigments were added, with what could have been a gum or animal glue, to the top, making aqueous binding.

 

 

 

It was seen from their first unearthing that the terracotta warriors were painted in brilliant pigments that included bone white, lead white, hematite, cinnabar, malachite, azurite, black ink, kaolin, red and yellow, ochre, minium, and yellow lead. It was also seen that in some cases they were gone in minutes. The colors had seemed to vanish into thin air. Others followed the same course in weeks and it was clear that something had to be done to preserve this history. The brainstorming began, but didn't produce anything significant until 2003 at a university in Munich, Germany.

Before I explain the process that was developed there I should first explain why exactly the pigments were fading other than their old age, and explain what the terracotta clay was treated with.

The warriors were originally coated with polychrome. Polychrome is a lacquer base topped with a layer of pigment. So that’s where scientists started in their quest to save Chinese history.

So why are the pigments disappearing, and disappearing so rapidly. Its really quite simple, and the process goes a little something like this; they are over 2,000 years old, all of which they have spent under ground. the ground absorbs water, which then comes in contact with the warriors that are buried in the ground. The water and moisture then alters the lacquer, cracking and peeling the coating. Because it is they are still under ground in the same extreme moisture environment, the paint stays intact. A farmer comes across them one day in field where he is digging a well, and they are unearthed. The lacquer, essentially, goes under an extreme environmental change and in response it cracks further falling off. So what do we do? Well its obvious that need to simulate their previous environment. To remedy that they are now currently housed in dome-like structures protected from the outside elements.

It was also noticed that the flashes of the tourist cameras were also deteriorating the warriors, so in subsequent years flash photography has been banned. There are also other factors such as dust and climatic change of thousands of visitors each year that makes the preservation of the warriors particularly difficult.

Many techniques have been tested by scientists (chemists) using different polymer-based materials to strengthen the polychrome and therefore secure it to the terracotta/pigment surface but the molecules were too big to penetrate the coating. The technique conceived by scientists in Germany called for an organic monomer that’s typically is used to make plastics, and that organic monomer used was hydroxyethyl methacrylate. They saturated cotton compresses with the monomer and a polymerzation and put it to the terracotta pieces of broken warriors. The water-soluble monomer replaced the water in the diffused coat's pores.

The next step was to irridate the fragments with electron beams using an electron accelerator. The electrons activated a polymerization agent which combined the monomers into polymers, consolidating the polychrome, or otherwise binding the terracotta and the polychromy. This process has been dubbed HEMA or HydroxyEthylMethAcrylate. This technique has only been used on fragments and seems to be working quite well. It seems quite possible that HEMA will be used on a full warrior in the upcoming years.

It seems to be quite clear and agreed upon by everyone that without conservation, the paints will be lost forever, along with great history.

Click here to be directed to the Emperor's home page.

Click here to take a gander at; His Rein.

Click here to learn about his quest for immortality.

Click here to ponder the Emperor's necropolis.

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That's all for now folks!

Click here to go to the AACE web page.