Bentonite、Montmorillonite Clay 、Absorbent Clay 、Swelling Clay、Smectite Clay

Bentonite (Montmorillonite Clay) Supplier

If you're sourcing Bentonite for a specific process — drilling fluid, foundry sand binding, pond sealing, pet litter, or oil clarification — the question that actually determines fit isn't "what is bentonite," it's which type and grade matches your application's swelling, viscosity, or absorbency requirement. Bentonite is a naturally occurring clay composed primarily of Montmorillonite, a mineral in the Smectite clay group, CAS 1302-78-9. What makes it commercially useful is its layered silicate structure: water molecules enter the space between the clay platelets, causing the material to swell — in some sodium-rich forms, up to 12-15 times its dry volume — while also giving it a large internal surface area that adsorbs ions, oils, and organic compounds. Which of those two behaviors — swelling or adsorption — dominates depends on which exchangeable cation sits between the clay layers, and that's the first decision point in sourcing the right material.

Sodium Bentonite vs. Calcium Bentonite 

Almost every sourcing mistake in this category comes down to picking the wrong base type for the job. Here's the practical comparison:

• Sodium Bentonite: high swelling capacity (typically 12-15x dry volume in water), high viscosity yield, forms a low-permeability gel and stable colloidal suspension | Best fit: drilling mud and fluid additive, pond and lagoon sealing, foundation and tunnel waterproofing, landfill liners, and any application where sealing or gel-forming performance is the priority

• Calcium Bentonite: lower swelling capacity, but stronger adsorption and decolorizing performance, generally lower cost | Best fit: foundry sand binding, pet litter, edible and mineral oil clarification/decolorizing, cosmetic and pharmaceutical carrier applications, and general absorbent clay use

• Sodium-Activated Calcium Bentonite: calcium bentonite treated with soda ash (sodium carbonate) to exchange calcium ions for sodium ions, pushing swelling performance toward sodium-grade behavior at a lower cost than natural sodium bentonite | Best fit: buyers who need swelling/sealing performance but are working with a calcium-based deposit or a tighter budget than natural sodium bentonite allows

If your specification calls for a defined swelling index or viscosity yield (common in drilling and civil engineering RFQs), confirm the exact test method and target value with us before ordering — natural sodium and sodium-activated material can look similar on paper but perform differently under load.

Choosing the right grade by application

• API / Drilling Grade Bentonite: sodium bentonite processed to meet API 13A viscosity and yield specifications, used as a mud additive in oil and gas drilling, water well drilling, and horizontal directional drilling to maintain borehole stability and suspend cuttings

• Foundry Grade Bentonite: typically calcium or activated sodium bentonite selected for green sand molding, providing plasticity for mold shaping, thermal stability under molten metal, and low burnout to reduce casting defects

• Civil Engineering / Waterproofing Grade: sodium bentonite for pond and reservoir liners, landfill caps, hazardous waste containment, canal lining, and pile foundation sealing — swelling pressure is what creates the low-permeability barrier

• Iron Ore Pelletizing Grade: bentonite used as a binder in iron ore pellet production, where swelling and green pellet strength are the key performance factors

• Absorbent / Decolorizing Grade: calcium bentonite used for filtering and decolorizing edible oils, mineral oils, and animal fats, and for regenerating used lubricating oils and dry-cleaning solvents

• Pet Litter Grade: sodium or activated calcium bentonite valued for clumping performance and odor control — particle size and dust control matter more here than raw swelling index

• Cosmetic & Personal Care Grade: calcium bentonite used as a carrier and thickening agent in masks, powders, and topical formulations, where purity and consistency across batches are the priority over raw swelling performance

Why source your Bentonite through us

Buyers across drilling, foundry, construction, and absorbent-clay applications are generally solving for the same core problem despite very different end uses: consistent swelling or absorption performance batch to batch. Because a shift in montmorillonite content or activation level between shipments forces costly re-tuning of dosing or mix ratios on your end.

Clear grade guidance so you're not left guessing between sodium and calcium bentonite for your specific process, and pricing that holds up once you've compared landed cost against other origins. 

That's the specific gap we work in — batch-tested CoAs documenting swelling index, viscosity, and moisture on every shipment, grade guidance based on your actual application rather than a generic one-size-fits-all listing, and flexible order volumes from trial quantities through full container loads.

Packaging & logistics

Standard packing: 25kg or 50kg PP woven bags with PE liner, or 500kg/1000kg jumbo bags for bulk buyers loading by container or truck. Both powder and granular forms are available depending on grade and application. Neutral packing and customized labeling are available for distributor and private-label accounts.

Frequently asked questions

Q：What's the actual difference between sodium and calcium Bentonite ? 

A:Sodium bentonite swells far more in water (up to 12-15x its dry volume) and is used where sealing, gelling, or viscosity is the priority. Calcium bentonite swells less but adsorbs and decolorizes more effectively, and typically costs less — it's the better fit for foundry, pet litter, and oil clarification use.

Q:Is Montmorillonite Clay the same thing as bentonite? 

A:Bentonite is the commercial name for a clay that's primarily composed of Montmorillonite, a mineral belonging to the Smectite clay group. In practice the terms are used close to interchangeably in trade, though "montmorillonite content" is the specific technical figure that determines a given lot's performance.

Q:Can you supply a specific swelling index or viscosity yield to match my drilling spec? 

A:Yes — provide your target swelling index or API 13A viscosity yield requirement and we'll confirm which grade and lot meets it before quoting.

Q:What's your minimum order quantity? 

A:MOQ is flexible depending on grade and packing — sample quantities are available for jar testing and quality verification before you commit to a bulk order.

Q:Do you provide a Certificate of Analysis and SDS? 

A:Yes, every batch ships with a CoA documenting the graded properties relevant to your application, and an SDS is available for handling and safety reference.

Get a quote

Tell us your clay type preference (sodium, calcium, or sodium-activated), target application grade, particle size, and destination port, and we'll come back with a specification sheet, CoA sample, and pricing for Bentonite — usually within one business day.

Application

To be used in drilling mud、to be used in iron ore pelletizing、to be used as foundry sand binder、to be used in engineering waterproofing and sealing in industry、to be used as absorbent and clarifying Agent in enviromental protection、to be used as desiccant and thickening and suspending agent in chemical industry、to be used as decolorizing Agent in food industry and other fields.