• by vinux

Nowadays more and more people fall in love with purple sand pot, and the background often has pot friends asking, which kind of clay material has the best air permeability?

Today I will give everyone a unified answer. There are two main factors affecting permeability, one is crystallinity, and the other is mud particle size.

Crystallinity is the degree to which a substance is composed of crystalline structures, as opposed to an amorphous form. It can be expressed as a percentage of the crystalline area relative to the total sample area. It is an important factor for many materials, especially polymers, as it affects their physical properties such as transparency and strength.

The degree of crystallization, which is the degree of vitrification during firing.

It is the intrinsic property of the mud itself, and the degree of crystallization after firing varies for different muds.

In addition, it is also related to the firing temperature. The higher the firing temperature, the higher the crystallinity.

This mountain’s green clay is fired at high temperature.

Generally speaking, the crystallinity of red mud is relatively high when fired, followed by purple mud and then green mud.

The higher the crystallinity, the lower the porosity and poorer breathability.

Therefore, among different types of mud, the air permeability of section mud is the best, followed by green mud, purple mud and red mud (but only relatively speaking, it can be ignored for tea brewing).

An old man, covered in mud.

However, in the process of drinking tea, breathability of clay is not the only selection criterion; it should be chosen according to different teas and drinking habits.

For example, the porosity of the mud and green mud is the best, and it is best to make green tea; the purple mud is moderate and broad, suitable for tea-making; red mud and cinnabar are more suitable for brewing high-scented teas such as Tieguanyin due to their porosity, which has a quick aroma and high fragrance.

Number of mud materials

The clay for making pottery is divided by its grain size, commonly 60 grains, 80 grains, etc. The smaller the grain size, the coarser the clay and the more obvious its granular texture.


The sand in the purple sand is also the fundamental reason for its breathability, so when sifting the mud material, the smaller the number of meshes, the larger the particles, and the better the breathability of the mud material made.

Under the same type of clay, the smaller the number of eyes in purple clay, the better the air permeability.

Different expressions of numbers

Generally speaking, 60 meshes of clay are better, with good breathability and rich sand feeling. Too many or too few meshes make it inconvenient to make a pot.

However, the porosity of coarse-grained pots may change slightly, but this difference is so small that even very precise and advanced scientific instruments may not be able to measure it.