Therefore, the purple pottery with uneven filling position is not a defective product as long as it does not crack and has no serious bulge or depression.
From the current level of technology, tight and smooth rotation of the lid is no longer a problem, because the pot makers have found an effective solution, that is grinding the pot mouth, which is called “whole mouth”.
Because of the nature of clay, Jianshui purple pottery has a large shrinkage rate, mostly in the range of 18% ~ 20%. For teapots and jars, the lid is separated from the can body. At high temperature in the kiln, the shrinkage of the lid and the can body will be different due to the properties of the clay, the thickness of the green body and the difference of the shape of the utensils. Some of them will deform slightly.
Kiln burning is a complicated process, in which there are many uncontrollable and unknown factors. The tight lid of the pot before entering the kiln may not be tight after firing. If the lid is smaller than the mouth of the pot, which is the common shaking of the lid, there is no way to remedy it. Most Taoyou can accept the slight shaking, but if the shaking is too much, it can only be treated as defective products or waste products.
In order to solve this problem, the commonly used method is to make the lid larger than the mouth of the pot or the mouth of the pot. After contraction, some covers can be tightly fastened on the mouth of the pot or the mouth of the pot, but most of the covers are still too large.
At this time, we have to carry out the “grinding pot mouth” process. Apply the high hardness emery powder to the mouth cover. With the help of the billet drawing machine, the lid rubs with the mouth of the pot and the mouth of the pot, and grinds off the surplus parts until the lid and the mouth of the pot fit together.
The vast majority of Jianshui purple pottery teapots, tea pots, there will be obvious traces of the whole mouth. Especially for the purple pottery with black surface, the black reducing layer on the surface will be worn off after friction at the mouth cover, and the red green body inside will be exposed.
Therefore, it is not a defect or a serious problem that the color of the flap is different from that of other parts, but that almost every piece of purple pottery has to pass through the whole mouth, which is one of the obvious and common characteristics of Jianshui purple pottery.