5 Things You Must Know About Tenmoku Glaze

1.What is ceramics glaze and tenmoku glaze

The glaze is a colorless or colored glass layer covering the surface of ceramics. Its main materials are quartz, talc, kaolin clay, plant ash, etc. These materials are ground into a glaze slurry in proportion, applied to the base cup, and then such a glass layer can be fired at a certain temperature.

The glaze may have been produced by the calcium-containing stones and charcoal ash used in the ancient piling stones for cooking. Glaze can increase ceramics’ strength and thermal stability, beautify utensils, facilitate cleaning, and prevent dirt erosion.

The raw materials of Jianzhan tenmoku glaze are obtained from local quartz and red clay in Jianyang. The iron content is as high as 8%. It is an iron-based crystalline glaze. It is also one of the main features of the Jianzhan Tenmoku glaze. Glaze with high iron content has many advantages. Make your tea taste better.

2.The ingredients and recipe for tenmoku glaze

The glaze of Jianzhan is made of a certain proportion of mineral soil (quartz) mixed with wood ash, and its components are as follows.

1) Glaze base. It is the base, mostly quartz (silicon oxide). The glaze ore of Jianzhan is mainly quartz but also feldspar, with high iron content and a small amount of clay. The color of the glaze obtained by panning is red, which belongs to the iron series crystalline glaze, which is very important for forming Jianzhan’s stunning pattern.

2) Coloring agent. It is also a mineral. For example, copper oxide turns green, and cobalt oxide turns blue, etc. Jianzhan’s chromogen is iron oxide.

3) Cosolvent. For example, feldspar and plant ash are a kind of cosolvent, which can help quartz lower the melting point. Different plants have different glaze effects.

As for the recipe of Jianzhan, just like the recipe of Coca-Cola, it is a trade secret, and no company will disclose its business secret. However, scientists have worked hard to determine its chemical composition, which may help you. Image below shows the details. For more: National Science And Technology Library Of China

3.The making processes of tenmoku glaze

First, carefully select the local feldspar raw materials in Jianyang, break the large stones into small pieces, wash them with clean water, clean the impurities inside, then we get the primary ore.

Secondly, we need a long cylindrical barrel with a plastic sealing device. Pour the cleaned ore into the barrel, add an appropriate amount of water and hard stones, and seal the mouth of the barrel.

Finally, we put the barrel on a machine that can be turned, start the machine and let the barrel rotate for a few hours. The hard stones in the barrel will break the ore, and then we get raw glaze slurry. After further filtration, we get a pure and usable glaze.

4.The main pattern of Jianzhan tenmoku glaze

The origin of crystalline glaze is that the crystalline substances in the glaze are saturated after melting during the product firing process, and crystallization occurs during the slow cooling process so that beautiful pattern crystals are precipitated.

This glaze characterized by crystallization is called the crystalline glaze. Tenmoku glaze is a typical crystalline glaze. The different formulations of the glaze, the temperature and heating conditions during firing, and the environmental changes during cooling, will affect the pattern of the glaze, resulting in different patterns.

1) Rabbit hair pattern

The rabbit pattern is a treasure of Jianzhan’s traditional craftsmanship. The black glazed surface is covered with brown or black lines, the shape of which is like a rabbit’s hair. Its shape is long, short, thick, and thin, and its color is gold, silver, yellow, blue, etc. Various categories. The stripes are the distinctive feature of this pattern. It looks like thousands of rays are released from the center. So dazzling.

2) Oil spot pattern

Because there are many small metallic color dots of varying sizes on the glaze surface, people call them oil spots, which are also very similar to the pattern on the feathers of partridge birds and are called “partridge spots.”

Its appearance is round or oval, and its colors are silver gray, yellow, silver, etc.; the pattern is unevenly distributed, aggregated, or loose, just like oil spots floating in the water, so people call “oil spots.”

3)Yohen pattern

Yohen tenmoku is a unique existence among many ceramics, and it is also very precious. Only three Yohen tenmoku cups from the Song Dynasty are left in the world, all of which are in Japan and recognized as Japanese national treasures.

The black glaze of the yohen pattern produces circular or similar circular spots of different sizes. The layout of the spots is not consistent. A few or more are gathered together. There are flashing rainbow colors around the spots when illuminated by sunlight or lights. It is accompanied by the fantasy color produced by the change of perspective, like the universe’s starry sky, which is fantastic.

5.How to appreciate Jianzhan tenmoku glaze

The most outstanding feature of Jianzhan is the natural pattern of iron crystallization. Its pattern is not artificially made and is varied. We can appreciate it from three perspectives of color, pattern, and texture. These three dimensions must be considered comprehensively rather than in isolation.

1)Color

Appreciating the colors of Jianzhan, first of all, you can start from personal subjectivity. Some people think blue and silver are simple but elegant, and some think pure brown is warm.

However, the recognized collection value must be combined with the rarity caused by the difficulty of firing. The same is true for the two dimensions of pattern and texture.

The order of difficulty of colors is roughly colorful>gold>blue>brown. Take the Yohen glaze color as an example. It presents colorful colors under the illumination of the light, so this color is the rarest.

2) Pattern

There are many patterns in Jianzhan, among which the more famous ones are Yohen tenmoku, rabbit hair, oil spots, glaciers, and so on.

The pattern of Yohen tenmoku is unpredictable, and it is very precious to be fired, so it is the best of all forms.

The oil spots need to be uniform in size, pure silver to a golden oval shape, evenly distributed, with clear boundaries, excellent vitrification, and a strong sense of metal. The more the oil spots meets this standard, the better.

Patterns such as rabbit hair and glaciers are in a radial shape, so the patterns are distributed orderly, the size is suitable, and the changes are naturally top grade.

3) Texture

The texture is subjective, but it is still an important factor in evaluating the quality of a product.

You touch or even tap the cups (the iron content of the cups is high, and the percussion sound will be clearer) and play.

Observing the details, and feel the product from visual, auditory, tactile, and other aspects, and then can it bring you visual beauty? Is there a “heavy” feeling, and is the artistry fine? These are all important.

6.Conclusion

Jianzhan Tenmoku cups have two major characteristics, one is the heavy feeling, and the other is the various beautiful patterns formed by the iron-based crystalline glaze.

We understand what porcelain glaze is, the iron-based crystalline glaze, how to make the glaze, what types of patterns are formed after the glaze is fired, and how to appreciate these patterns. I believe you already have a relatively complete and clear understanding of tenmoku glaze.