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Bentonite Clay

Bentonite is referred to as the “The Clay of 1000 uses.”

Foundries, well drillers, iron ore manufacturers, and producers of kitty litter are the main consumers of Bentonite.

Foundries use Bentonite when pouring metal cast molds. The clay withstands higher temperatures and the excessive heat will not cause the clay to lose its chemical structure.

Well drillers use Bentonite when drilling oil or gas wells. Bentonite will absorb 10 times it weight in water. The bentonite clay is mixed with water and other minerals to form a drilling mud, which seals up the wall of the well bore and allows the rock chips to be pumped back to the surface.

Iron ore manufacturers add Bentonite to crushed taconite to form pellets, which can then be transported to a steel mills.

Because Bentonite will absorb moisture, new applications are continually being developed. Clumping cat litter and toxic waste cleanup are two of those new markets.

Bentonite is also used as a:

  • Clarifying agent for wine, vinegar, fruit juice, beer, oils
  • Sealant in sanitary landfills and lagoons
  • Water purification systems
  • Binder in fertilizers and animal feed products
  • Carrier for insecticides

We stock the following qualities:

“Western” Bentonite Qualities (Sodium Type):

This type of Bentonite is a sodium based Bentonite – it swells approximately 15 times their un-wetted volume.

Western Bentonite in molding sand blends aids in deep pocket molding to maintain its dimensional accuracy.

Primary use is in the production of ferrous and non-ferrous castings. Western Bentonite results in a greater dry/hot strength than southern Bentonite.

“Southern” Bentonite Qualities (Calcium Type):

This type of Bentonite is a calcium based Bentonite – it swells only two times their un-wetted volume.

Southern Bentonite provides greater green compression strength and permeability than Western.

Bentonite and has lower hot retaining strength.

The lower strength aids in shakeout and reduces stress related defects.

Blends of Southern Bentonite molding sand often reduce mechanical penetration, which results in uniformly dense molds.

Primary use is in the production of non-ferrous castings.

Opta Minerals has long time experience in advising and supplying Bentonite and providing technical support to our customers.


  • 50 lb paper bags
  • 2200 lb Super Sacs