BENTONE 38 and VG‑69 are brand names for organophilic clay — the viscosifier and suspension agent of oil-based and synthetic-based drilling fluid. Organoclay is a clay-chemistry product manufactured by specialist factories for several industries, which is exactly why buying it by specification matters: drilling grades and paint grades share a name and a chemistry family but are built for different jobs. Ironstone supplies OBM-grade organophilic clay with a certificate of analysis for every batch.
Ordinary drilling bentonite works in water and does nothing useful in oil. Organophilic clay is bentonite or hectorite whose surface has been treated with fatty quaternary amine compounds, which turns the clay from water-loving to oil-loving. Dispersed into the oil phase of an invert system — with proper shear — the treated clay platelets build the gel structure that gives the fluid its viscosity and its ability to suspend barite and cuttings. It is the OBM counterpart of what bentonite does in a water-based mud, and it is usually the backbone rheology product of the whole invert formulation.
Organoclay factories sell into coatings, greases, inks, and drilling — and the grades are tuned differently: a paint-grade clay is optimized for fineness and gloss behavior in a resin system, a drilling grade for yield, temperature stability, and suspension in diesel, mineral-oil, or synthetic base fluid. The sacks can look identical, the base clay is the same family, and non-drilling grades exist at lower price points. The protection is simple: require performance data in a reference invert mud, not just a chemistry description.
Both exist as legitimate drilling products — BENTONE 38 is hectorite-based, while most drilling organoclays are bentonite-based. The base mineral affects cost and performance profile, but no name on a sack settles the question of which your system needs. The honest selection method is the same as for every product on this page: equal dosage, your base fluid, your temperature, measured side by side.
| Parameter | Why it decides the match |
|---|---|
| Yield in a reference invert at stated dosage | The core job — the viscosity the clay builds in your base fluid at your dosage, after proper shear. |
| Base-fluid compatibility | Diesel, mineral oil, and synthetics activate organoclays differently; a grade proven in one is not automatically proven in another. |
| Temperature stability | The gel structure must survive bottom-hole temperature for the section, not just the pilot test. |
| Suspension performance | Low-shear readings and sag behavior — the reason the product is in the mud at all. |
| Dispersion / shear requirement | How much mixing energy the clay needs to develop yield — a practical constraint on rigs with limited shear. |
Build a lab invert with your field formulation and base fluid, and run candidate against incumbent at equal dosage: rheology after hot-rolling at your bottom-hole temperature, low-shear readings, sag, and electrical stability. Organoclay is the backbone of the invert’s rheology, so we treat it like the OBM filtration class: full lab sequence, then a pilot volume, then — and only then — switch the program. We quote this class with lab data attached, because that is what an honest organoclay offer looks like.