Pottery glaze fired

Pottery glaze is a vitreous coating applied before firing, providing waterproofing, color, and gloss to the finished piece.

About this subject

The technique of glazing pottery dates back thousands of years, with evidence from ancient Egypt and Mesopotamia around 4000 BCE. Glaze is a mixture of silica, fluxes (such as feldspar or metal oxides), and colorants that melts during firing at temperatures ranging from 900°C to 1300°C, forming a hard, glassy surface.

In Japan, the tradition of glazing porcelain reached artistic heights with the Seto kilns and the tea ceremony. In Europe, the discovery of hard-paste porcelain in the 18th century at Meissen, Germany, revolutionized fine tableware production. Today, potters and industries use low-fire and high-fire glazes, each with distinct properties: low-fire glazes (like lead glazes, now restricted) are bright and colorful, while high-fire glazes (such as stoneware) are more durable and matte.

Notably, glaze color can change drastically with firing temperature and kiln atmosphere. Copper-bearing glazes produce green in oxidation and red in reduction. The famous oxblood red (sang-de-boeuf) is a high-fire glaze using copper oxide in a reducing atmosphere. Beyond aesthetics, glaze waterproofs the piece, preventing liquid absorption and ensuring hygiene for food use.

Frequently Asked Questions

What is pottery glaze made of?

Glaze is made of silica (glass), fluxes that lower the melting point (like feldspar or calcium carbonate), and metal oxides for color (copper, iron, cobalt).

How is glaze applied to pottery?

It can be applied by dipping, brushing, spraying, or pouring. The piece must be dry and dust-free. After application, it is fired in a kiln.

What is the difference between glaze and paint?

Paint remains on the surface and can peel. Glaze fuses with the body during firing, forming a permanent, vitrified coating that is durable and waterproof.