top of page


  • Johannes Scott

GLAZE: introduction

The ancient technology of glazing pottery was discovered in Mesopotamia and Egypt in about the 8th or 9th century B.C. A glass-like, transparent surface was achieved by mixing ash or soda with sand and applying it to the surface of pottery before firing. The Greeks followed with lead glazing, employing lead oxide mixed with sand.

The purpose of glaze was to seal or waterproof the porous earthenware clay since the technology of vitreous, high firing stoneware was not available in ancient time.

In China around A.D. 1 to 250, Taoist alchemists experimented with materials such as lead, copper, and tin to prolong the physical life expectancy of humans. Early experimentation with these materials set the later technological stage for Chinese ceramists to import Persian knowledge on combining lead oxide with copper oxide and sand (silica) to produce earthenware glaze.

It is likely the Chinese were the first to make the conclusive observation of the glass-like effect ash glaze deposits have on kiln furnace and kiln interior walls that led them to develop the technology of high-firing stoneware, by A.D. 650.

In the 15th century, German technology discovered the effect of inserting salt into the kiln atmosphere during the firing process. The salt insertion causes an atmospheric ‘airburst’ that ‘contaminates’ all the surfaces in the firing kiln, depositing a glass-like surface onto the entire kiln interior – this led to the discovery of salt-glazed stoneware. This technology was industrialized in Europe to produce vitreous ink and ginger beer bottles and drainpipes.

The Persians discovered tin glazing around A.D. 1100. This mixture of kaolin and feldspar produce an opaque, white surface and marks the advent of the decorating technique that became known as maiolica during the Renaissance.

Today, glaze is generally applied by either spray airguns, dipping, and brush coating. For example, spraying for industrialised tiles or sanitary ware and dipping for factory produced dinner services.

In our studio, we employ the brush-on method because glazes are purchased in small quantities for individual application to artwork.


Gracht Gallery


Tuesdays: 10h30 - 14h00

Wednesdays: 10h30 - 14h00

Thursdays: 10h30 - 14h00

ad hoc

and by appointment

First Thursdays: 17h00 - 20h00 


160 Buitengracht Street


Cape Town

South Africa

082 859 9900

Join our mailing list

bottom of page