Tuesday, July 12, 2022

Handbuilding at ORPG - Week 6 - Early Glaze History

 June 30, 2022

This week we will spend time completing our surface decoration. This is in two parts:

a) complete painting with underglazes (commercial or coloured slips).
b) applying dipping glazes to bisqueware or apply commercial glazes (gloss, satin, matte)

The pictures below are taken from Chinese glaze history. I include these because there are important parallels to what we are doing or that I have referred to:

Above: Neolithic Terra cotta
(bottom left is Minoan)

 Left:  terra cotta, Tang Dyn.,
lead glaze (3 colours - Sancai)
   Right Above: terra cotta,
                                                   Qin & Han Dyn. 231 BC-220AD, lead glaze

Low fire glazing (see pictures above)
The Chinese used this approach on terra cotta. This clay would fire between 700-900F (wood fired to cone 06, 05). They developed a lead based clear glazed and applied this over coloured surfaces (minerals). We begin to see this glaze in the small figurines of the Han Dynasty.

High Firing - Stoneware and glazing

Sturdy stoneware glazing requires a hotter wood firing; gradually the kilns became longer and moved up on an incline. This reached cone 6 in proto celadon works and cone eventually cone 10/11. The firing often lasted two weeks and many in the village participated.

High Firing Porcelain
At the same time new clay materials were being experimented with such as porcelain (addition of white kaolin) and refinements in making a smooth clay body.

Top Left: Proto celadons (Proto Porcelain 1046BC-256BC)
Top Right: More refined celadons (550-577AD)

Celadon on Stone ware. This is a feldspathic glaze. Ash would also contributed to glossy surface. Reduction fired. c.581-618 AD.

Early porcelain. Petal design, Guan Kiln, Tang Dynasty 618-907AD

White glaze porcelain. Pillows popular from Sui Dynasty 581AD-Yuan Dynasty 1368

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