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Ball Clay

A rare rock you’ll find on your dinner table.

What is Ball Clay?

Ball clays are kaolinitic sedimentary clays that commonly consist of 20–80 percent kaolinite, 10–25 percent mica, and 6–65 percent quartz, along with small amounts of organic matter.

Ball clays are fine-grained, highly plastic clays, which are principally used in the manufacture of ceramic whiteware and sanitaryware where they are appreciated for their plasticity, unfired strength and their light colour on firing. Selected clays can even give pure white end products.

Among others, ball clays are also used in refractories, in polymers, in adhesives and sealants and in horticulture as soil amendments.

The name “ball clay” is derived from its early extraction methods in 18th century England when it was dug by spade as cubes, which then became rounded during subsequent transport.

Today, ball clay is extracted using hydraulic excavators, working at “benches” cut into the quarry to access the seams of clay. Individual raw clay selections are carefully blended according to pre-determined recipes to yield a product with a consistent and predictable range of characteristics and behavior. The first stage in processing is then to shred (or “kibble”) the blended clay into smaller, more regular lumps about the size of a golf ball. Much blended clay is sold in this shredded form.

Further processing through drying and grinding yields powdered ball clays, and treatment by calcination produces “chamotte” or “grog,” calcined clay containing a high proportion of silica and alumina. Ceramics manufacturers (particularly in the sanitary ware sector) have also benefited from the development of refined ball clays and chamottes which offer improved performance and reduced manufacturing process costs. Refined clays are available in “noodled” and slurried form.

  • The use of ball clay in ceramics dates back at least to Roman times.
  • Today’s common practice of shredding ball clay for commercial use originated in the 1930s using mobile turnip-cutting machines.

Where to Find Ball Clay

Uses for Ball Clay

Ceramics Ball clays form a vital component in ceramic manufacturing. Used with kaolin, which has limited plastic properties, ball clay provides the cohesion and workability necessary for the creation of ceramic parts. As a result of their sedimentary origin, raw ball clays have a wide range of colors. Many of them are valued by the ceramics industry for their white-firing properties, which are determined by the amount of metallic oxides within the clay.
Soil Amendments & Hydroponics Added to soil, ball clay pellets increase water retention and drainage. In hydroponics, they keep plants hydrated while saving water.
Sanitary Ware Sanitary ware typically includes chamotte and ball clay as essential components, with the ball clay providing plasticity and workability. In addition, sanitary ware includes kaolin, feldspar, and quartz.
Tableware Ceramic tableware uses ball clay combined with kaolin, feldspar, and quartz to provide high plasticity and a good, white-fired color.
Wall and Floor Tiles Again, combined with feldspar, kaolin and quartz, ball clays are used for their plasticity and bonding properties.
Glazes Plastic clays are also used in the production of coatings for ceramic products to ensure the perfect finish.
Refractory Clays The ability to resist the effects of extremely high temperatures makes ball clay and chamotte ideal for use in refractory products, such as kiln insulation and furniture.
Construction Ceramics Building materials, such as bricks, clay pipes, roof tiles, and pavement sealers, all contain ball clay.
Electrical Porcelain Insulators You will find ball clays in the electrical porcelain components that provide insulation from high-voltage currents.
Chemical Applications Ball clays are used as fine fillers and extenders in polymers, adhesives, plastics, fertilizers, and insecticides.
Sealants Ball clays are also widely used for lining landfill waste disposal sites and for sealing over them once completed.

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