“Mud door” is a term often heard by enthusiasts of purple clay teapots. What does it mean? Simply put, it's a term used to describe the density or tightness of the particle distribution in the clay body of a Purple Clay Teapot after firing. Low density is referred to as loose mud door, while high density is called tight mud door. Specifically, it relates to the preparation of the clay, the use of a slicking tool, and the pot-making technique.
When identifying whether a teapot is fully Handmade or semi-handmade, checking if the tightness of the mud door is consistent inside and outside the pot is one of the key methods. In brief, a fully handmade teapot is formed by hand using a Bamboo paddle, so the characteristic of the mud door on the body is tight on the outside (surface) and loose on the inside (interior). The particles on the outer surface are densely distributed and become even tighter after the application of a slicking tool. However, the inner wall has not been pressed hard by hand but rather lightly shaped, so the particle distribution in a fully handmade teapot is relatively loose, meaning the mud door appears loose. A semi-handmade teapot, on the other hand, has its body formed by pressing the clay against a mold with the hand or a tool, applying similar force both inside and out. Therefore, the tightness of the particle distribution in the clay, both inside and out, is quite similar in a semi-handmade teapot, meaning the mud door tends to be tighter. This should be easy to understand.