Bone China by John Shirley

John with his translucent work in South Africa

In 2000 while studying for my BTech in Ceramic Design I decided that I wanted to work in a translucent body (up until this time I had always worked with porcelain) but I wanted to try something I had not worked in previously.

It was then that I chose bone china as the medium I wanted to explore. This has really been an exciting journey and bone china is the body I still work with today.

​The body is traditionally fluxed with bone ash and feldspar and stabilised with Kaolin. Fired to 1250C it produces a body of extreme whiteness and excellent translucency.

​As a ceramist living in South Africa where the choice of raw materials is more limited and the quality is less regulated than in many other countries, I was determined to make a translucent body with local materials. This is where my choice to work with bone china really paid off. What I discovered is that the bone ash in the body acts as a bleach on any traces of iron present in the kaolin in the body. As the local kaolins are far from the extremely white kaolins available overseas this proved to be a real bonus.

Antoinette Badenhorst discussed the translucency of the porcelain and bone china soluble salts with John during her visit in Bryanston, South Africa

​I started with the usual recipe of 50% bone ash, 25% Feldspar and 25% Kaolin which I made into a casting slip, as bone china is almost impossible to throw. Although my first results were not ideal they were very promising and I adjusted this first test. I tried many different kaolins. I changed from bone ash to tri-calcium phosphate which is synthetically produced. And within a few months arrived at a recipe that produced the results I was aiming for. With a few tweaks from time to time this is the recipe I still use today.

​The body has a high shrinkage and a tendency to warp in the firing and although I have tried several ways to stabilize the body in the firing with various setters, I now accept the gentle warping produced by the firing as a part of the process.
Choosing to work with bone china for my work is I feel something that has worked really well for me and the work I produce with this body is quite different to any work I would have produced using the porcelain body I was using before.

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Links:

• Demonstrations, tips and techniques at TeachinArt
• Click here for the video Antoinette interviews John Shirley
• John Shirley website www.johnshirleyceramics.com 
• Antoinette's blog about difference between various kinds of porcelain