My system is not decent

Chapter 1045 Unintentional and Unintentional Action
Does the agate glaze have much effect on the properties and color of the porcelain glaze layer?

The glaze color and glaze surface of genuine Ru porcelain do not depend on whether agate is added to the glaze?

Agate glaze is just a pile of materials, just a reflection of royal luxury?

Chen Wenzhe certainly does not agree with these views, because the facts are obviously not the case!
First, there is no precedent for agate glaze, and there is no one to come. There were no official kilns in the Northern Song Dynasty, nor in the Southern Song Dynasty, nor in the Ming and Qing Dynasties.

Since Song Huizong was able to build the "Hua Shi Gang", why not transport gems from all over the country as raw materials to produce "Northern Song Official Kiln" products?
In fact, the agate used in the Ru kiln was not the favorite of the emperor, it was an invention of the local kiln workers;
Second, the emperors of the Ming and Qing Dynasties cherished Ru porcelain and imitated it many times. Wouldn't it be possible to use gemstones as glazes?
In fact, Ming imitation and Qing imitation of Ru porcelain cannot achieve the effect of Song Dynasty Ru porcelain;
The "Tianqing glaze" porcelain fired in imitation of Ru in the Kangxi period is quite rare, but it is not made by reduction firing with iron, but the glaze color is fired with cobalt as a colorant. The effect and difficulty are not comparable to the Ru kiln porcelain in Song Dynasty comparable to.

Third, why is only agate glazed and not other gemstones?
There are many quartz gemstones, such as crystal, opal, tiger spar, etc.;

There are many gemstones in the whole country. Why don't other kilns use gemstones as glazes, but Ru Kiln only uses gemstones?

All kiln mouths are fired with local materials, which is in line with objective facts.

Ru kiln craftsmen's "agate glaze" is an innovation, and it is the pursuit of excellence for Ru kiln craftsmen to burn the azure color of Ru porcelain to the extreme.

Ye Zhi of the Southern Song Dynasty recorded in "Tanzhai Biheng" that "in this dynasty, the white porcelain in Dingzhou had awns and was unusable, so Ruzhou was ordered to make blue kiln wares. Therefore, Tang, Deng, and Yaozhou in Hebei have all of them, and Ru kiln is the first." Be real and believable.

Ruzhou is a large place with many kilns, but only the Ru kiln of Qingliang Temple in Baofeng is the best.

The preciousness of Ru kiln lies in its shape and glaze color, and there must be reasons for the agate to be glazed.

The luster of Ru kiln porcelain is very reserved and restrained, as soft as silk and as warm as jade, which is in line with the traditional Chinese concept of modesty and restraint.

However, it is very difficult to make the luster of the porcelain glaze implicit and not dazzling, and the glaze needs to be thickened to achieve it.

This requires the addition of alkali metals to the calcareous glaze in order to be able to hang thick glaze.

However, the earlier lime glaze flowed as soon as it was hung thick, and it was difficult to achieve a subtle and warm effect, which was limited by the historical conditions at that time.

Therefore, Ru kiln craftsmen boldly broke through the tradition and invented agate glaze.

The first time Ru kiln craftsmen added agate as a substance, it must have been done unintentionally.

Just like adding malachite to the Jun kiln, it was an unintentional move, and the result was copper red glaze.

Agate has a waxy luster, birefringence, and high refractive index, which must have a very important impact on the azure color, opacity, and jade texture of the glaze.

The discoloration effect of the Ru porcelain glaze under sunlight is also the result of light reflected by the birefringence characteristic of agate.

The porcelain glazes of other kilns cannot be compared with it.

Ru porcelain has a lime glaze with a thin glaze layer. The official kilns and Longquan kilns of the Southern Song Dynasty have lime alkali glazes, which have a jade texture after multiple glazes.

Seeing this, Chen Wenzhe gained a lot, especially the knowledge about agate glaze.

In addition, he discovered that there were two deviations in his cognition. One was that the glaze of agate had little to do with the azure color of Ru Kiln.

Although he knew that the glaze of agate was related to the glaze color of Ru kiln porcelain, but he really didn't expect that the relationship was so big.

Another thing is that Ru kiln porcelain may use lime alkali glaze, so that thick glaze can be applied.

But after seeing the firing process of Ru kiln and the lessons learned by Yan He, he knew that things were not what he imagined.

First, the glaze of agate is very important. It is related to the color change and shape of the porcelain, as well as the texture of the glaze, especially the jade-like texture.

The second is that the Ru kiln porcelain is applied with lime glaze instead of lime alkali glaze. However, the craftsmen of Ru kiln also produced thick glaze.

And this kind of thick glaze is different from the thick glaze of lime alkali glaze.

In comparison, Ru kiln glaze is thinner, but the effect it shows is not worse than that produced by lime alkali glaze in the Southern Song Dynasty.

And this must be related to the glaze of agate. Without the additive of agate, pure lime glaze would definitely not be able to achieve the effect of Ru kiln porcelain.

These techniques are all real stunts!

If he hadn't seen the firing process of the piece of Ru porcelain in front of him, if he hadn't seen Yan He's works, how could he know these secrets?

There is a certain relationship between the azure color of Ru porcelain and the glaze of agate. As long as the research is thorough, it will be easy to make high-quality Ru porcelain later.

After seeing some secrets, Chen Wenzhe really understood that the emergence of the concept of the azure color of Ru porcelain is inseparable from Song Huizong's pursuit of art.

However, the actual firing of porcelain of this color has benefited from the wisdom and skills of Ruzhou porcelain craftsmen back then.

After seeing the production process of Ru kiln porcelain, Chen Wenzhe really understood the importance of agate glaze.

Combined with some modern research, Chen Wenzhe is more aware of the problems inside.

There are many reasons why agate is glazed. The first one must be known to ancient ceramic lovers. The biggest difference between northern enamel and southern enamel is that the north is a low-silicon and high-aluminum kiln with high temperature;
In the south, it is high in silicon and low in aluminum, and the firing temperature is relatively low.

The firing temperature of the northern glaze is high, and the high firing temperature will lead to a heavy color of the porcelain body, which is not conducive to obtaining azure color, but after the agate is glazed, this situation will be improved.

The main component of agate is silicon dioxide. Adding agate to the glaze can increase the silicon content in the glaze, while reducing the proportion of aluminum and lowering the firing temperature of the glaze.

At the same time, it can also control the color of the porcelain body. It should be known that the higher the firing temperature, the darker the color of the porcelain body. These characteristics are more conducive to obtaining azure color.

In addition to this, agate glaze can also affect the enamel.

The enamel of Ru porcelain is a typical lime glaze, and the flux-calcium oxide content in the glaze reaches about 15%.

If agate is not added to the glaze, if the firing temperature is lowered to obtain azure glaze color, the glaze will not be fully fired and the body will be underfired.

However, at high temperature, exceeding 1220°C, it is easy to burn into glassy glaze, and does not have the opacity jade texture quality.

Moreover, the content of iron oxide in Ru enamel is as high as 2%.

This is comparable to the glazes of the official kilns of the Southern Song Dynasty and the glazes of Longquan kilns, both of which have high iron content and are not as thick as them.

In the high-temperature reducing atmosphere, the ionic iron is abundant, and the glaze is fully melted, so that only turquoise glassy glaze can be obtained, and the opaque jade texture of azure blue cannot be obtained.

Adding agate to Ru glaze reduces the firing temperature of the glaze, which is conducive to obtaining opaque jade-like enamel.

How could Chen Wenzhe know these things if he hadn't seen them with his own eyes?

Of course, the ancients definitely didn't know the reason, but they slowly figured out the best firing formula and process through long-term practice.

(End of this chapter)