A fine-grained ball clay with excellent plasticity and strength. Old Mine #4 is an "industry standard" based on its popularity in both casting and plastic formed bodies. It is also widely used as a suspension aid in
glazes. OM#4 ball clay is variable in nature and tends to be more vitreous than some of the more refractory ball clays that are available. It has some soluble salts which can give a brown coloration to the surface,
so barium carbonate may be needed to precipitate these. The term 'ball' traces to historic mining in England where large chunks of the clay were cut from the bank in ball shapes for transport to processing.
There are hundreds of different ball clays available and they vary widely in plasticity, particle size, color, firing properties. A typical ball clay powder is light grey (from lignite) or cream color and fires to a buff or cream
white color with some soluble salt deposits on the fired surface. They are typically vitrified at cone 10. Ball clays are very plastic and much finer grained than kaolin. Ball clay is the main plastic material used in
clay bodies of all types. It is much more plastic than kaolin but also has much higher dry shrinkage and higher iron content. Ball clay is a fine particle clay that is universally used in glazes for suspension.
Larger amounts are available
