• by vinux

Pure raw ore superior clay often shows various defects when fired, but this is not absolute. In order for the special defect phenomenon of pure raw ore superior clay to appear, it must meet one or more of the following conditions:

The bottom of the pot cracked (after firing for the first time).

One: “It must be an ore with a certain sandiness”.

Two: “The purity of the ore and the raw material screened out must be sufficiently pure.”

Three: “The mud material must be pure sand particles, or the fat powder mud contained in the mud material should be absolutely low during smelting.”

Why are there so many inexpensive and perfect kettles on the market?

Why are there so many machine-made teapots and hand-pulled kettles on the market now? This has something to do with most new pot friends, who don’t want to accept flaws, thinking that they have spent money, which won’t tolerate any flaws. Some people don’t even look at the quality of true or false. Many new pot friends think that it looks good, but in fact it is wrong. There are many purple sand pots made from machine blank, perfect and attractive in price, dozens of blocks, more than one hundred plus six cups for free, a lot on Taobao. After all, it’s because of the lack of understanding of purple sand!

What are the common flaws in raw ore?

Nuggets (raw ore material often appearing, which is a normal phenomenon)

“Explosions, Bombs, and Bomb Mud”.

These phenomena usually occur with pure sand particles, or those with very high sand content. As the pot is fired in the kiln, it shrinks as a whole. Some slightly larger particles burst due to the sudden temperature difference between inside and outside. There is no buffer around the particles, so they explode.

This phenomenon can be reduced by controlling the temperature rise and fall rate of the kiln, but most people do not have their own kiln, and even if they have a kiln, they may not be able to master the firing method, so preventing such problems is still a difficult task.

The root cause of this situation is low plasticity, insufficient tightness of the mud during production (not hard enough for pinching), and uneven force during opening, which causes defects. Even top masters cannot avoid defects in such material.

Flower mud (can be covered up with conditions).

“Flower mud”: A type of clay used in Chinese pottery and ceramic crafts, made from a combination of fine-clay powder, plant fibers, and other natural materials.

The main reason is that the sand particles are hard and the mud material is pure. The density of the grease mud used to connect the pot mouth and the body sleeve is different. If the later kneading process is not enough, or when the clay is not moistened, use a pin to cause the sand grains to fall off, Or if the finished mud is placed for a long time, the moisture inside and outside of Zisha mud material will be different, which will cause it.

Therefore, it is best to re-refine the finished mud used for making pots before it is stored for a long time, or repeatedly hammering. Usually it is only very slight flowery patterns before the pot is crystallized, while most of the time they appear after crystallization.

Therefore, do not reject teapots with blossom mud phenomena as they are genuine purple-clay teapots. Although they may not be aesthetically pleasing, some blossom mud phenomena can be nurtured away.

“Ash explosion”:

Because the particles of limestone are embedded in pure purple sand, they will become lime when heated and swell. Due to the small buffering force of pure sand, it will burst and form ash explosion.

The fundamental cause of the formation of cracks or fissures in the surface is that the sand is pure. As the saying goes, the clay is explosive and the viscosity is very low. Many pure hard sands have filaments and cracks on the surface, most of which can only be seen with a magnifying glass, but they do not leak water. This situation is very normal.

Mud burst (too large to impact usability and aesthetics, classified as defect).

“Explosive defects, mud explosion”: a phenomenon caused by a process defect where the product is damaged and fragments are scattered.

This type of mudded material usually has good sand purity, high hardness, and slightly larger particles, which generally appear in forty to sixty mesh hard mud materials. The main reason is the kiln method and atmosphere in the kiln. If the temperature rises and falls too quickly in the kiln, large particles will burst due to the large difference between internal and external temperatures, resulting in bubbling or defects. Some materials are fine but also may show this phenomenon due to their relatively low ore texture when they are heated too quickly or beyond their firing temperature in the kiln.

Jump sand (very slight, does not affect use, can’t be seen without a magnifying glass).

Jump sand.

The reason for forming sand jumps is very simple, that is, when firing, the body of the pot shrinks, there is no cushion between the sand particles and the sand, and the smallest adhesive strength sand is pressed out.

From this point of view, most of the teapots with bouncing sand phenomenon are pure superior hard sand. To eliminate the bouncing sand phenomenon is very simple, just add a little fat powder mud into the mud material. Although it will not bounce sand anymore, the mud quality has also decreased at the same time.

Iron black (too large in area, unable to use, considered as a defect).

The melting point of iron (too small to be noticed, not considered a defect).

“Iron black, iron melt”: Iron is strong and resilient, but when heated to its melting point, it is transformed.

Iron black: It refers to the iron that has melted under the skin of the pot due to high temperature but has not yet been decomposed. Iron melt: It refers to the crystalline iron that has melted and decomposed on the surface.

When the pure raw material is fired to a certain temperature, most of them will appear iron black and iron melting phenomenon. Purple sand clay with iron black is quite common, and the quality of the material is generally not bad.

Only raw ore can produce iron melting mud, and it must meet the following two conditions: one is that the mud must be screened pure sand particles or very low fat powder content. Second, regardless of whether it is soft mud or hard sand mud, the mud must be burned to basic crystallization, that is to say, it needs to be burned into purple sand pot.

Looking at these two points, a pot with a melting point of iron is definitely an excellent quality clay. The cause of the black and melting iron has not yet been scientifically diagnosed, but may be related to the purity of the original ore. On the other hand, even if the ore is best, if it is impurely smelted, it will not have a melting point of iron.

The purple clay teapot made from raw ore mud has a different look after being wrapped with clay.

After the pot was glazed, a closer look revealed the mineral deposits common in purple sand, black spots.

These phenomena are mostly found in the raw ore mud material, and people with high recognition of porcelain will generally not reject the normal defects appearing in the superior mud material. People with low recognition of porcelain cannot accept any defects.