---
title: 'Teaware material and firing'
url: 'https://howtotea.me/science/material-and-firing'
markdown: 'https://howtotea.me/science/material-and-firing.md'
lang: en
date: '2026-11-03'
description: 'How clay, porcelain, glass and metal change tea, and how the kiln sets the color and density of the body: porosity, preheating, reduction, wood firing.'
---

# Teaware material and firing

Preheating and the mass of the wall matter more to the cup than the kind of clay. Color and density are settled in the kiln.

 ![A multi-chamber climbing kiln of clay and brick under a shed roof](https://howtotea.me/images/c/o/v/e/r/cover-3ca6dd80.webp) Photo: [T.Kiya from Japan](https://commons.wikimedia.org/wiki/File:Shigaraki_climbing_kiln_(21753734429).jpg), [CC BY-SA 2.0](https://creativecommons.org/licenses/by-sa/2.0), cropped 

Teaware comes wrapped in legend, and labs in Taiwan, Japan and mainland China have put much of it to the test. They measured the [material itself](https://howtotea.me/science/material-and-firing/teaware-materials): zisha clay has 8–13% porosity compared with 2.4–2.6% for porcelain, while porcelain conducts heat only slightly better. Sencha brewed in iron-rich clay came out about a fifth lower in tannins than sencha brewed in porcelain, with no difference in amino acids. Preheating matters most: in a cold 100 ml vessel, the water cools by about 20 °C within a minute. The "breathing" wall and the teapot's "memory" rest on interpretation, not measurement.

Body density, and with it porosity, is set during [firing](https://howtotea.me/science/material-and-firing/kilns-and-firing). When the kiln is starved of oxygen (CO at 4% and up), iron in the raw material turns the glaze celadon blue-green and the body gray; with oxygen to spare, the tones go yellow and brown. Zisha is fired at 1100–1200 °C; porcelain goes to around 1300 °C and comes out absorbing only about 0.5% water. Wood firing is prized for its ash and unpredictability, but there is no solid evidence that it changes how tea tastes.

In this section

- [![](https://howtotea.me/images/c/o/v/e/r/cover-188d96d6.webp) Teaware materials How clay, porcelain, glass and metal change the brew: porosity, water absorption, heat capacity and vitrification. What tests confirm and what stays myth. ](https://howtotea.me/science/material-and-firing/teaware-materials)
- [![](https://howtotea.me/images/c/o/v/e/r/cover-f5d6e249.webp) Kilns and firing How the kiln sets the color and density of teaware: oxidation and reduction, wood, gas and electric firing, and yaobian. What it means for your cup. ](https://howtotea.me/science/material-and-firing/kilns-and-firing)

---

## Navigation

- Parent: [Tea science](https://howtotea.me/science.md)
- Previous: [Tea evaluation and tasting](https://howtotea.me/science/evaluation.md)
- Children:
  - [What Teaware Is Made Of: Porosity, Heat and Vitrification](https://howtotea.me/science/material-and-firing/teaware-materials.md)
  - [Kilns and Firing: Reduction, Wood and Kiln Change](https://howtotea.me/science/material-and-firing/kilns-and-firing.md)