1, cover the gray process

Cover the gray process is mainly a high iron content of alabaster pots fired in a reducing atmosphere, so that the raw material in the form of iron oxide exists in the form of change. Under normal firing conditions, the formation of iron oxide crystallization in the original alabaster most of the hematite fired in a reducing atmosphere, hematite is reduced to magnetite crystals, so cover the surface of the gray products have a certain degree of adsorption of magnetite.

Zisha clay such as green clay, such as a part of the lower iron clay is generally not suitable to cover the ash fired (cover the ash fired more gray ink color, color effect is not good). Covered ash fired Zisha pots, such as in the neutral - oxidizing atmosphere of the kiln to re-fire, the price will return to the original color.

As early as the Ming Dynasty, master alabaster craftsman Chen Zhongmei already used the methods of sand blending and sand laying to enhance the decorative effect on the surface of alabaster wares.

2, the sand process

In the processed clay or powder, according to the requirements of a variety of sand particles with a certain size and proportion, in order to improve the density of particles.

The particles and the base mud belong to the same mineral, known as the color of the tone of the sand; the particles and the base mud do not belong to the same mineral, known as the different color tone of the sand.

This color sand into the original mud, because the mud texture is the same, after firing the tire color will not produce large changes, but the mud in the particles of the increase in the content of the main role in strengthening the skeleton of the billet. For some of the softer particles, particles also need to be 600-800 ℃ firing to increase the strength of the particles, otherwise the particles in the molding process is easy to be crushed by the tool and caused by the surface of the vessel trailing phenomenon.

If most of the Zhuni clay shrinkage and deformation rate are relatively large, not conducive to the production of large works alone, need to rely on the method of sand to increase the strength of the blank, so that the blanks after the firing of the overall shrinkage and deformation to reduce, improve the rate of finished products fired. Therefore, most of the modern Zhuni pots are mixed with coarse sand particles or supported by clinker (clinker is the powder that is ground into the finished clay after firing).

Different color sand will produce different color effects depending on the color and texture of the particles and the base clay. If the transfer of particles into the hard nature of the particles, after firing, the surface of the ware particles protruding, coarse pear skin; when the transfer of particles into the soft nature of the particles, after firing, the surface of the ware will produce a fine concave point. The softer the particles, the more pronounced the dots, forming a texture effect like orange peel.

4, laying sand process

Playing sand refers to the purple sand blank in the production process, the different clay color sand particles using the method of paving, pointing, spreading, etc., applied to the surface of the blank still have a certain degree of humidity. And then with the help of tools will be embedded in the surface layer of the blank. The sand mainly plays the role of decorative embellishment, so that after the firing of the surface of the purple sand ware into the sand point and the tone of the tire form a sharp contrast effect.

The texture of the sand particles is generally required to be higher than or equal to the texture of the blank particles. If the texture is softer, it will cause the particles to drag and after firing due to the shrinkage of the particles and tire incompatibility phenomenon.

5, sand extraction process

Sand extraction is in the processed powder or slurry to separate out a certain part of the specifications of the particles. In the 40 mesh powder extracted 60-80 mesh particles, so that the remaining particles and fine material firing to form a coarse and fine obvious contrast effect, resulting in a new texture.

Expanded Information:

Usage Characteristics:

(a) Zisha is a porous material with a double pore structure

The pores are microscopically small and highly dense. Making tea in a Zisha pot does not lose the original flavor.

(2) Zisha pots have good air permeability

The use of its tea is not easy to change the flavor of the summer days, the more overnight not rancid. Long time no use, there will not be a host of gas, as long as the use of the first full storage of boiling water, immediately dumped, and then immersed in cold water rinse, the energy can be restored, the tea still get the original flavor.

(3) Zisha pot can absorb tea

The inner wall of the pot is not brushed, tea and absolutely no odor. Purple clay pot after a long time of use, the wall of the pot to accumulate "tea rust", so that the empty pot into the boiling water, will also be heavy tea, which has a certain porosity with purple clay pot tire, purple clay pot is unique quality.

(D) zisha pot hot and cold performance

cold winter months, the pot into the boiling water, absolutely not due to sudden changes in temperature and cracking. At the same time, sand heat transfer is slow, after tea holding will not be hot. And can also be placed on the fire cooking heating, will not be cracked by the fire.

(E) the longer the use of purple sand

The more the color of the pot is bright and shiny, the charm of elegance. Zisha pots used for a long time, the body will be stroked and wiped, become more and more moist and lovely.

Baidu Encyclopedia - Purple Sand Pot