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INTERNAL COMBUSTION CERAMICS

This revolutionary ceramic concept was inspired by Pre-Columbian dung fired art and pottery.

With Clayton Bailey's Internal Combustion technique, the fuel (dung) is mixed into the clay before firing.

A mixture of 50% Horse Manure and 50% clay body is used. As soon as the clay has completely dried, it is placed in the kiln and ignited with a flame. Heat is efficiently generated within the walls of the ceramic object, not in the walls and flues of the kiln.

This collection of test tiles demonstrates Clayton's discovery of Horseclay, and explains his Internal Combustion Ceramic process:

1- Mix together 50% pulverized Quarter Horse Manure and 50% Clay.

2- Add water, and use the clay immediately. Prolonged storage will cause sprouting of the seeds in the manure.

3- Ignite the object with a flame when it is thoroughly dry. (Works best in an insulated kiln chamber.)

4- The fired object is light and porous. The honeycomb structure of the fired clay makes Bare Hands Raku possible.

Many cultures have fired their ceramics with dried dung : a man in England propels his automobile with methane from chicken droppings.

These two ideas led me to wonder if I could mix manure with clay to produce "self-firing" ceramics. The fuel could actually be put inside the clay!

After much trial and error, I found that horse manure had the most desirable characteristics, it is plentiful and when dried, it is pleasant to work with. Pulverized horse manure consists of a fine dark powder and short fibers. The powder soaks down like slip while the fibers give the wet clay strength and rigidity. When the fibers burn away, a porous structure remains.

I have been using a mixture of fifty percent pulverized dry horse manure (quarter horse manure is best), and fifty percent regular clay body. After forming the Horseclay, it must be dried immediately to prevent the disintegration of your work by sprouts and plant development. Horseclay can be stored in a refrigerator to prevent sprouting.

This clay will provide approximately eighty percent of its fuel requirements for low-fire work if it is brought to ignition temperature in an electric kiln. The firing works like this: the kiln is tightly sealed and rapidly heated to the ignition point of manure (500 degrees Fahrenheit). A lack of oxygen in the kiln chamber causes the formation of methane gas. At 500 degrees, air vents are opened at the bottom of the kiln to admit air. A quantity of smoke will be suddenly released. At this point the electricity can be shut off since combustion of the methane will cause a continued rise in temperature inside the kiln.

A well insulated and tightly packed kiln chamber will attain a maximum temperature of approximately 2000 degree Fahrenheit before the methane supply is exhausted. The length of time required for this will depend upon the thickness of the pieces.

Chicken and duck manure can be added to increase plasticity of the clay and to raise the percentage of nitrates which will help to vitrify the clay. Dog and cat manure have proven to be undesirable to handle.

Clayton Bailey - (From a letter to the editor)- Ceramics Monthly Magazine -1971