"Every brick kiln has its own personality. This one is very mild and tender, and the color of green it produces is light," Zhang says.

He points to another one standing in front of the village, which in his words is "fierce" and its products are heavy in gloss. A good firing needs half a year of preparation.

After many firings, a craftsman knows the kiln inside out, and learns how to control the precise temperature by watching the color of the flame, or by using a piece of clay as a measure. The heat can reach as high as 1,310 C.

No matter it's a brick kiln or a modern one, the craftsman's aim is to pursue a glaze of exquisite beauty, with their own unique input.

"Just like a chef, we have our own formulas to produce different shades of green, a color similar to jade," says Zhang, adding that they can expertly identify the various shades of green by eye.