Bentonite for Pesticide Formulations: How to Choose for SC and OD Systems

Start with the FormulationSystem
Selecting bentonite for a pesticide formulation starts with understanding the liquid medium, the active ingredient, and the performance required from the finished product.
A useful purchasing enquiry should explain more than “we need pesticide-grade bentonite.” It should identify the formulation type and the problem to be solved, such as sedimentation, difficult redispersion, or inconsistent viscosity.
This article focuses on two liquid formulation types: water-based suspension concentrates and oil dispersions. It explains the selection questions to address before approving a mineral rheology additive.

1. Understand the Difference Between SC and OD A suspension concentrate, commonly abbreviated as SC, contains solid active ingredient particles dispersed in an aqueous continuous phase. Its formulation requires appropriate wetting, particle stabilization, and rheology control. These are related functions, but they are not interchangeable. An oil dispersion, abbreviated as OD, contains solid active ingredient particles dispersed in an oil-based continuous phase. Depending on the formulation, the carrier may include mineral oil, vegetable oil, or methylated seed oil. The product must also behave appropriately when diluted with water before application. This distinction matters when selecting bentonite. A material that performs well in water should not automatically be approved for an oil-based formulation. When discussing an “oil-based suspension,” confirm the actual continuous phase and intended formulation classification rather than relying only on the informal product description.

2. Evaluate Water-Dispersible Bentonite for Aqueous Systems Selected water-dispersible bentonite grades can be considered as mineral rheology additives for suitable aqueous agrochemical formulations. Commercial hydrophilic clay additives are used to develop thixotropic behavior in aqueous crop-protection products. Their technical guidance also emphasizes appropriate incorporation and hydration before evaluating performance. For a candidate inorganic bentonite, begin by confirming its intended application and recommended dispersion procedure. Then assess it in the complete formulation—not only in a clay-and-water mixture. A useful screening plan should include the actual process water and the intended dispersants, wetting agents, and other formulation components. Record the water quality, formulation pH, addition sequence, and conditioning period so that the trial can be repeated. Do not assume that every inorganic bentonite will give the same result. Request grade-specific information and establish acceptance criteria around the finished formulation.

3. Select Oil-Compatible Grades Separately for OD Formulations For an OD project, an organophilic bentonite may be a candidate for evaluation, provided its compatibility with the carrier and additive package is established. Commercial agricultural rheology products include organically modified clays dispersed in vegetable oil. This illustrates the importance of selecting a clay treatment and delivery form suited to the intended medium; it does not establish that all organoclays are equivalent. Ask the supplier to clarify the candidate grade’s intended carrier range, incorporation procedure, and any activation requirements. Evaluate these conditions before deciding whether the material fits the available manufacturing process. Also keep the different additive functions separate. In an OD formulation, the rheology modifier helps control sedimentation, while dispersants support particle stabilization and emulsifiers enable the oil phase to disperse into water during dilution. A clay additive should not be assumed to replace this complete additive package. Good swelling in water is not proof of suitability in oil. Treat the use of an aqueous inorganic grade in an OD formulation as an unverified application until the complete system has been tested.

4. Test More Than Initial Thickness Do not approve a candidate solely because the freshly prepared sample looks thick. Define a practical evaluation that covers the concentrate, the diluted product, and changes during storage.

Evaluation area                        What to examine
Rheology                     Apparent viscosity under recorded instrument settings and conditioning conditions Sedimentation            Separation, sediment character, and ease of redispersion
Handling                   Pourability and residue remaining in the container
Dilution performance               Suspensibility for the relevant SC system; dispersion stability for the relevant OD system
Coarse material              Wet-sieve residue and other relevant particle-quality checks
Storage stability          Changes in physical properties, active ingredient content, and packaging condition

Regulatory guidance for SC and OD products includes these types of physical and chemical assessments. Select the applicable methods and acceptance limits for the actual formulation and target market.

When assessing suspensibility, distinguish the active ingredient remaining suspended from the total suspended solids. A clay-rich sample can appear well suspended without demonstrating that the active ingredient is distributed correctly; use an appropriate validated analytical approach.

For internal screening, identify every sample by formulation code and batch reference. Record the addition level, dosage basis, mixing history, and test conditions. Repeat promising trials before moving to production-scale evaluation.

5. Microbial Pesticides Require a Separate Viability Assessment When the active ingredient is a living microorganism, physical stability is only part of the evaluation. A fungal-spore formulation may remain visually uniform while its biological activity changes. Depending on the organism and product, suitable assessments may include viable counts, spore viability or germination, and relevant biological activity tests. OECD guidance distinguishes these measurements from simple weight-based determination of the microbial material. Include microbial compatibility in the evaluation of the complete formulation. Do not assume that a mineral is compatible with living spores merely because it is described as natural, or that an organoclay is suitable merely because it provides good suspension. Storage conditions also need to match the organism and intended product. Standard high-temperature accelerated tests used for chemical pesticides should not be transferred automatically to living microbial formulations. Use an organism-appropriate study design supported by technical justification. Reduced settling does not, by itself, demonstrate preserved viability or improved biological performance.

6. Define What “Pesticide Grade” Means for Your Purchase For a purchasing specification, do not rely on the application label alone. Agree on the identity, measurable properties, and documentation required for the proposed use. Request clarification of the clay type and whether it has been organically modified. Discuss moisture, particle-size information, relevant impurities, dispersion behavior, and the test conditions used to describe rheological performance. Separate typical values from contractual specification limits. Where a supplier reports viscosity or swelling data, ask how those values were measured before comparing them with another product. Also distinguish raw-material qualification from finished-pesticide qualification. FAO/WHO pesticide specifications address pesticides and their formulations; a description such as “pesticide-grade bentonite” should not be presented as evidence that the finished product has obtained approval or meets a particular pesticide specification. Confirm the applicable documentation and regulatory requirements for the intended market before commercial use.

7. Prepare a Useful Enquiry Before Requesting Samples A clear enquiry helps narrow the selection and avoids testing materials in unsuitable systems. Describe the formulation type, active ingredient or microorganism, continuous phase, approximate solids loading, current rheology additive, and principal performance issue. Include the manufacturing equipment and any restrictions on ingredients or processing. For an OD project, identify the carrier oil and the dispersant–emulsifier package as far as confidentiality allows. For an aqueous project, provide relevant water-quality and pH information. An initial enquiry could read: We are evaluating a mineral rheology additive for a pesticide suspension formulation. Our main targets are reduced sedimentation and easier redispersion after storage. We can share the formulation type, carrier, current additive, processing conditions, and evaluation criteria to discuss a suitable candidate. This is a starting point for technical discussion, not a formulation recipe.

Discuss Bentonite Selection with Hermano Hermano New Materials (Dalian) Co., Ltd. supplies bentonite materials for agrochemical applications. The company’s pesticide-formulation product page provides an entry point for discussing material selection. Contact Hermano with your formulation details and testing objectives. Before arranging a trial, confirm the candidate grade, intended medium, available technical documentation, and incorporation requirements. Approval should be based on repeatable results in the agreed formulation rather than on a generic application claim. Related product: Bentonite for Pesticide Formulations. This article provides general material-selection guidance. It is not a pesticide formulation recipe, a regulatory approval, or a performance guarantee. Grade-specific suitability, biological compatibility, and finished-product performance require appropriate evaluation.

Technical References
Croda Agriculture — Technical guidance on suspension concentrates and oil dispersions.
BYK — OPTIGEL-CK technical information on hydrophilic clay rheology additives and aqueous agricultural applications.
Elementis — BENTONE GEL AG1 product information illustrating an oil-based organoclay dispersion for agricultural formulations.
APVMA — Guidance on generating storage-stability data for agricultural chemical products.
OECD — Guidance Document on Storage Stability of Microbial Pest Control Products.
FAO/WHO — Pesticide specification guidance.

These references provide technical background.

They do not constitute certification, endorsement, or performance evidence for a Hermano product.