Shi Potian talks about Zisha: Why does Zisha need to adjust sand?

The so-called sand adjustment is to add a certain proportion of coarse or fine cooked or half-cooked sand when practicing purple sand clay . (It is especially emphasized here that the cooked sand is burnt purple sand mud and does not contain chemical raw materials). I believe that many friends who are new to teapots will have doubts: Don’t they all say that they are made of raw ore purple sand material or pure purple sand material? Why adjust the sand? Pure is not good? Is the sand adjusted or is it real purple sand?
There is a saying in the purple sand circle: mud is meat, and sand is bone. Experts say that there are "bones" in purple sand mud. This "bone" is the quartz particles in the purple clay, which is the "sand" in the purple clay. Sand mixing in mud is not shoddy, let alone cutting corners. Sand adjustment is a very old craft. Our ancestors had to add a certain proportion of sand when firing ceramics. The sand adjustment process of purple sand has also existed since ancient times. There are naturally many benefits in it. Let me briefly talk about sand adjustment various benefits.
Sand adjustment can reduce shrinkage during firing. The shrinkage rate of various components in the raw purple sand mud is also uneven, while the sand does not shrink during the firing process, and the sand adjustment is convenient for reducing the shrinkage rate during firing and molding, and improving the yield.
Sanding can enhance the texture of the finished product. A certain amount of coarse sand or fine sand must be added to the purple sand mud. Of course, the mud and the adjusted sand must be even and proper. After firing, the surface of the pot can be full and even, and the texture of the pot surface is also strong.
Sand adjustment can enhance the plasticity of mud. In the pot-making process, if the mud material is too thick, it will be laborious to make, and if it is too thin, it will be easy to stick to the hand. It is also convenient to make pots by adding suitable sand.

Sand adjustment can improve the air permeability of the finished pot. Because the finished product contains a certain proportion of sand, the double pores of the finished pot are improved, the air permeability is improved, and it is more conducive to making tea.
Sand adjustment can also promote the moist feeling of the finished product and help control the color. Experienced clay masters will adjust the firing temperature and color by adjusting the sand while ensuring the texture of the purple sand remains unchanged. For example: adding yellow sand to the bottom tank, the kiln temperature only needs to be between 1120 and 1160 degrees. This can not only reduce the firing temperature, but also improve the texture and moisture of the purple sand. Therefore, what we see is that the color of the purple sand products that are also mud cleaning materials for the bottom tank varies greatly.
Different periods, different ages, and different masters in history have different representative clay colors and sand-adjusting characteristics, which also provide collectors and purple sand connoisseurs with connotative evidence for the appreciation of historical works. A good purple sand pottery, especially pots, in actual use, the texture changes on the surface of the pot body, giving people a comfortable, fine but not greasy feel, like the texture of bean paste and mahogany, elegant and charming, pleasing to the heart .
In order to pursue a unique visual effect, the predecessors used techniques such as sand adjustment, sand spreading, and sand embedding to spread and embellish the pre-screened, evenly granulated cooked sand in the mud, on the prepared mud sheet or on the pot embryo. as decoration. It produces various textures such as fine pear skin, dragon sand, and snowflakes. This kind of pot has a full sense of sand, simple and generous, and extremely attractive.