What is Bentonite?

Sodium bentonite is an absorbent swelling smectite clay consisting mostly of montmorillonite. Upon contact with moisture, the volume of sodium bentonite enlarges by approximately fifteen times its dry volume. 

Bentonite Properties

Bentonite contains a significant percentage of smectite. In clay mineralogy smectite is classified as a 2:1 clay. This is because it consists of one octahedral sheet positioned between two tetrahedral sheets. One layer is alumina while the other two are silica.The three layer crystalline structure described classifies it as a clay mineral. Smectites may swell when water enters in between the clay layers. The constitution of smectites consists of layers of aluminosilicate sheets which are negatively charged. Charge balancing exchangeable counter ions, such as NA+ or even CA2+, actually hold the sheets together. Hydration of these cations forces the clay layers apart. This ultimately results in the swelling of the bentonite.





High Plasticity

Bentonite Products

Bentonite Pond Seal

Granular Seal

Bentonite Chips

Drilling Mud

Sodium Bentonite: Environmental pond and soil sealant

Atrium Lightweight Materials offers natural sodium bentonite as an effective pond and soil sealant. The versatile and hygroscopic characteristics of natural sodium bentonite make it the ideal material for the safe sealing of ponds, lagoons and various infrastructure applications. The flexible, expanding and self sealing bentonite properties are intrinsic when precluding the permeability of water into a soil. Other options such as liners or concrete are usually static and unable to adjust to a change in soil especially in a climate with a variable freeze thaw cycle. Sodium bentonite is organic by nature while simultaneously maintaining its effectiveness.

What is Sodium Bentonite?

Sodium bentonite is a colloidal clay sealant that has multiple applications. These include sealing landfills, ponds and sewage lagoons. Bentonite is also utilized in plugging up drilling holes. Sodium bentonite is known as the clay of 1000 applications. It is a clay which consists of a combined plate structure and a surface which includes sodium ions. Once exposed to water these sodium ions hydrate which generates a negative charge on the bentonite plate. This negative charge causes the plates within the structure to separate which results in “swelling.” This is how bentonite derives its unique sealing attributes. Sodium bentonite is a flexible clay with a high plasticity. It never becomes rigid, sets or cures so it is not subject to tearing or cracking.

Sodium bentonite clay is recognized as an effective and affordable method for treating porous soils and sealing pools of toxic waste along with abandoned water and oil wells. 

What is the role of Sodium Bentonite?

Sodium bentonite clay performs well as a sealant because of its thixotropic interaction with water. Once hydrated sodium bentonite will swell up to 15 times its original size. Its successful performance as a sealant has been affirmed over several years of research. This is also why the United States government has required all landfills and waste disposal sites utilize sodium bentonite as a soil sealant in order to preclude leeching and contamination of hazardous chemicals into ground water. Due to the manner in which the bentonite swells it forms a strong watertight and chemical-proof sealant. A sodium bentonite soil sealant system facilitates the development of freshwater and effluent storage lagoons. Many municipal sewage oxidation lagoons have operated effectively for many years utilizing an economic bentonite soil sealant system. Industrial sanitary landfills utilize bentonite for effective leachate seepage control. Any potential future leak is precluded by the natural sealing smectite activity within the structure of the sodium bentonite. 

Pond Sealant

Pond Sealer
When it comes to sealing ponds and preventing leaks, utilizng sodium bentonite is essential.
A Pond Sealer
When it comes to sealing ponds and preventing leaks, using a quality pond sealer is particularly important.
Pond Sealer
When it comes to sealing ponds and preventing leaks, utilizng sodium bentonite is essential.

Pond Sealant

Pond Sealant

When it comes to sealing ponds and preventing leaks, utilizing a quality pond sealer is essential!

Application Methods


This product serves a wide range of brands in the "Creative, Reality, Arts & Music" industry


This product serves a wide range of brands in the “Creative, Reality, Arts & Music” industry

Mixed Blanket

This product serves a wide range of brands in the “Creative, Reality, Arts & Music” industry


This method is utilized when dealing with the presence of an existing body of water. This is usually due to a water body which cannot be drained or only a portion of it requiring treatment. Granular bentonite is highly recommended when using this method in order to avoid any swelling or gelling of the material before it settles at the bottom. The bentonite will be drawn to the cracks and crevices where the leakage is taking place. It is recommended to use 1 LB of bentonite per square foot of area covered.


This method is recommended when there is a significant amount of water loss via seepage. The process is as follows: The pond or lagoon must be fully drained. The area must then be cleared of all debris, vegetation and rocks. Remove 3 to 4 inches of sediment from the bottom and set it aside. Holes and crevices should be filled at a ratio of 5:1 of soil mixed with bentonite Once applied level the grade to eliminate any pits,dips or material buildup. Apply sodium bentonite at a rate of 1.25kg or 3LB per square foot Pack the bentonite to a similar density of the original soil Carefully refill the area with water without disturbing the packed bentonite and soil.

Mixed Blanket

This method also requires that the pond or lagoon be completely drained. Follow the same procedure as the blanket method except for every 100 square feet spread out 200-250kg of bentonite and spread it as evenly as possible. At this point you can rototill the area with the bentonite to a depth of 6 inches. Once completed begin the compaction process and then refill the pond or lagoon slowly so as to not disrupt the compacted area.
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