Black glaze is divided into two kinds
in the ancient times. One is lime glaze, the other is lime-
alkali glaze. The black glaze in the early period of Donghan
and Dongjin are all belong to the lime glaze. But after the
Tang Dynasty, the lime-alkali glaze was begun to use basically.
According to the variety of the black glaze, they are divided
into two kinds: the common black glaze and the colored black
glaze. The colored black glaze includes oil-spot glaze, hare's
fur glaze, turtle shell glaze, sesame paste glaze and so on.
| Oil-drop glaze is one special variety
of the black glazes. The characteristic is that many small dots
possessing silver grey metal luster scatter on the cover coat.
They are differed in size. The big one is several millimeters
in diameter and the small one is only as big as the point of
a needle. Their shape just like oil-drop. Therefore, it is called
"oil-drop glaze". Oil-drop glaze belongs to the crystalline
glaze. When it is fired, the oxide of the iron centralized here.
But these parts forms supersaturation state when it is cooled.
Moreover, there are crystals separated out in the form of sanguine
and magnetite. Therefore, it forms "oil-drop" spot.
The oil-drop glaze is first fired in the Song Dynasty.
Judged according to the products handed down from the ancient times,
this kind of black glazed ware possesses typical characteristic
of the Jiang ware. But this kind of ware is not unearthed from the
kiln site. On the contrary, they are unearthed from the "dingyao",
Hebi kiln and Linfen kiln in the North. Among them, the products
unearthed from the Lin Fen kiln are the most. The oil-drop crystallized
spots on the Ding ware and Hebi ware are very small. But they possess
strong silver lustre.
| The stripe of the yellowish brown
or iron rust is appeared on the surface of the black glazed
ware. Its shape like hare's fur. Therefore, it is called hare's
fur spot. Hare's fur is the rare variety of the black glaze.
During the process of firing, the air bubble in the glaze brings
the iron element to the cover coat. The part containing rich
iron element flow to the stripe shape as the running of glaze
at the high temperature of 1300 centigrade. The small crystals
are separated out when it is cooled. This
kind of small crystal is sanguine. Therefore, it forms
gorgeous hare's fur spot. The hare's fur has already emerged at
the beginning of the Song Dynasty. "yuhao", "yihao",
hare's fur spot, "tuhejinsi" and so on are often mentioned
in the poems of the successive dynasties. They are different names
of the hare's fur. The black calyx with hare's fur design is fired
at many porcelain kilns in Fujian Province. Therefore, it is called
hare's fur calyx. Among them, the products made in Jiayang kiln
are the most famous. The hare's calyx is also fired at some porcelain
in Jianxi, Sichan, Shanxi and other places. But the number of the
products less than the products made in Fujian.
Turtle shell glaze
Turtle shell glaze made in Jizhiou kiln. The cover
coat is mingled by black, yellow and other colors. Its color tone
is soft. The body of the turtle shell glazed ware is made of the
porcelain clay containing little iron content. Then, it is glazed
on the green body. After it is fired in the kiln, the glaze possessing
different swell factor is coated on the body. Moreover, it is fired
again. It forms the stripe of the tortoise-shell in black because
of the chapping, flowing, intensive and joint of the cover coat.
Therefore, it is called turtle shell glaze. The specimen imitated
turtle shell glaze made in Jizhou kiln has been found in the Guangxi
area besides Jizhou kiln.
Partridge feather spot is also a kind of crystalline
glaze. Two kinds of black glaze containing different iron content
are glazed on the green body twice. Then, it is fired by the temperature
lowing slightly to other crystalline glazes. Because there are a
lot of iron elements crystallized in the glaze, the black cover
coat takes on design like the feather of the partridge. Therefore,
it is called partridge feather spot.