Clear cement is a kind of purple sand mud, which is characterized by the color and texture of the pottery, and usually shows the effect of purple redden. Clear cement is the name of modern people, and there is no such term in history. The definition of clear cement is also not fixed, and different periods have different understandings and uses.
Qing cement first appeared in the early Qing Dynasty, when Qing cement refers to the selection of a single raw ore mud, without any other mineral materials or chemical pigments, crushed and processed, directly mixed into the mud. This kind of mud is delicate and ruddy in color after pottery. For example, people usually call the mud refined from the bottom groove green ore clear cement, and the bottom groove green can be regarded as clear cement, but the clear cement is not necessarily the bottom groove green. The purple sand mud made without mixing with any other mineral or chemical materials can be called clear cement.
In the ** period, the concept of clear cement has changed. Since there is no "clear cement" in the purple sand raw ore mud, people call the most common homogeneous purple mud ore in some purple mud muds according to the effect of pottery. The color of these mud mud is darker and coarser than the modern clear cement, and the color is not as bright as the clear cement in the early Qing Dynasty, so now people call it "** clear cement".
In the 60s and 70s of the 20th century, the concept of clear cement has undergone new changes. Yixing Zisha No. 1 Factory mixes the excess purple mud used to make purple sand blanks with red mud blanks and ordinary purple mud materials, and the processed mud is called clear cement, which is the so-called "Cultural Revolution Qing Cement". This kind of clear cement is mainly used to make low-grade products such as flower pots, which is a low-grade coarse mud, which is far from the clear cement of the early Qing Dynasty and **.
In the late 80s, due to the relative reduction of high-quality purple sand ore, people gradually paid attention to the clear cement (purple mud) originally used to make large road goods out of the aesthetic pursuit of the original material texture. The originally ordinary clear cement suddenly became a best-seller and became a hot spot in the purple sand market.
Now the industry will not be doped with other minerals or chemicals, after the work is fired, the purple mud with reddish color is called clear cement, also known as red clear water, and the purple color is called "purple clear water", which is not wrong. There are not a few purple mud ores used for refining cement, and there are more or less outputs in Huanglong Mountain, Dingshu Town, and the surrounding mines, and the surrounding areas of Yixing, among which the "Red Dragon" purple mud produced in Huanglong Mountain, Dingshu Town is the most representative.
The red skin dragon is a purple mud mineral material that is more commonly used in the purple mud of Huanglong Mountain. It belongs to the purple mud mineral, because the performance of the mud and the color of the appearance of the original ore and the color change after firing are the same as the purple mud. Although the appearance of the red-skinned dragon is reddish after firing, it is essentially purple mud. It is not produced in wild mountains, and it does not belong to red mud, so some people used to call it "wild mountain red mud". If the red mud produced outside the Huanglong Mountain is called "wild mountain red mud", it is not unavoidable.
The purple mud of the red-skinned dragon is distributed under the quartz sandstone (Huangshi layer) at the body bone of the dragon in Huanglongshan, and the burial is shallow compared with other purple mud. The raw ore is purple-red, tan-colored, block-like, silty mudstone structure, dense, heavy and hard. The mineral composition is mica, kaolin, quartz, mica detritus and ferrite, etc., and there are many mica impurities. The main chemical components and percentage content are: silicon dioxide (SiO2) 6354%, aluminum oxide (Al2O3) 2103%, ferric oxide (Fe2O3) 759%, titanium oxide (tiO2) 025%, magnesium oxide (MGO) 067%, calcium oxide (CAO) 052%, potassium oxide (K2O) 186%, sodium oxide (Na2O) 031%, loss on ignition 648%。
The red skin dragon is a relatively common purple mud mineral, and some people call it "Pu Zi". The quartz content of Hongpilong purple mud is relatively high, the coarse and fine particles are reasonable, the plasticity is good, the dry and wet are easy to master, the molding is easy, and the large and small pieces of works are suitable for production. The stability of the red skin dragon is good, the firing yield is reduced, and the temperature is easy to control, and the firing temperature is 1170 1190. After firing, the color of the appearance changes from brown-red to dark red and purple-red.
The red dragon is one of the best minerals used to refine clear cement, but it is not the only mineral used to refine clear cement. In recent years, in the process of national and local infrastructure construction, a lot of mud similar to the red skin dragon has also been excavated around and around Huanglong Mountain. Although the overall performance of these muds is similar to that of the red skin dragon, the texture is either not clear enough after pottery, or the texture is very clear, but it is not easy to soak and raise.
When using clear cement, it is worth noting that in the process of clear cement, the organic matter in the mud is easy to free from the mud surface and become flower mud, so the clear cement that has been stored for a long time must be cleaned with clean water before use, otherwise it is easy to produce black wires. This may also be the case with other muds. Qing cement works are soft and elegant, good affinity, easy to make tea, a little use, ruddy and simple, ancient and dignified, for the public's favorite.