Table of Contents
Bone China
Bone China is a type of soft-paste porcelain that is composed of bone ash, feldspathic material, and kaolin. It is defined as ware with a translucent body containing a minimum of 25% bone ash, though higher quality products often contain up to 45% to 50%.
Known for its high levels of whiteness and translucency, bone china is the strongest of the porcelain or china ceramics, having very high mechanical and physical strength and chip resistance.
1. Characteristics
- Translucency: When held up to a light source, bone china allows light to pass through. This is its most distinctive feature.
- Color: It has a warm, milky white or ivory tone, rather than the stark “blue-white” of hard porcelain.
- Weight: It is remarkably lightweight yet exceptionally strong due to the added bone ash.
- Resonance: When tapped gently, high-quality bone china produces a clear, ringing sound.
2. Composition and Production
The quality of bone china is largely determined by the percentage of animal bone ash (typically from cattle) in the clay body.
| Component | Percentage (Approx.) | Function |
|---|---|---|
| Bone Ash | 25% - 50% | Provides translucency and strength |
| Kaolin (China Clay) | 25% | Gives plasticity for shaping |
| Cornish Stone (Feldspar) | 25% | Acts as a flux to bind materials |
The Firing Process: Bone china undergoes two separate firings:
1. **Biscuit Firing (1250°C)**: The body shrinks and becomes vitrified. 2. **Glost Firing (1150°C)**: A lower temperature firing to melt the glaze onto the surface.
3. How to Identify Real Bone China
If you are a collector or buyer, use these three tests:
- The Light Test: Hold the piece up to a lamp; you should clearly see the outline of your fingers through the material.
- The Sound Test: Flick the rim with your fingernail; it should sustain a long, musical “ring.”
- The Visual Test: Look for a warm, creamy tint rather than a cold grey or blue tint.
[Image of bone china cup held up to light showing translucency]
4. Care and Maintenance
To preserve the beauty and longevity of your bone china:
- Dishwasher Safety: Most modern bone china is dishwasher safe. However, pieces with gold or platinum rims should always be hand-washed to avoid abrasion.
- Thermal Shock: Avoid extreme temperature changes (e.g., pouring boiling water into a very cold cup).
- Storage: Place felt or paper dividers between stacked plates to prevent surface scratches on the glaze.
5. Notable Manufacturers
- Wedgwood (United Kingdom)