Technical Specifications
| Property | Unit | Typical Value | Test Method |
|---|---|---|---|
| Barium Content | % | 7.8 | ASTM D4951 |
| Barium Sulfonate | % | 53 | ASTM D3712 |
| Viscosity @ 100 °C | mm²/s | 70 | ASTM D445 |
| Flash Point | °C | 200 | ASTM D93 |
| Moisture Content | % | 0.3 | ASTM D95 |
| Mechanical Impurities | % | 0.03 | ASTM D473 |
| Humidity Cabinet — Copper 10# | A | ASTM D1748 | |
| Humidity Cabinet — Brass 62# | 1 | ASTM D1748 | |
| Appearance | Brown transparent liquid | Visual |
* Typical values from batch production. Batch-specific COA available on request.
Technical content reviewed by the CheMost additives team · Specifications last reviewed
Molecular Structure
Molecular structure · barium sulfonate
(R–C₆H₄–SO₃)₂Ba (R = long-chain alkyl)
Barium salt of a long-chain alkylaryl (petroleum) sulfonic acid; the divalent Ba²⁺ cation gives the strongest sulfonate rust film and demulsibility.
What Is Barium Petroleum Sulfonate?
CheMost-B50 is an oil-soluble barium petroleum sulfonate (corrosion inhibitor) based on the barium salt of natural petroleum sulfonic acids. It is supplied as a brown transparent liquid containing 7.8% barium and 53% barium sulfonate, and is one of the most widely used film-forming rust inhibitors in industry — providing a high level of corrosion protection together with excellent resistance to emulsification.
Among the sulfonate rust inhibitors, rust-prevention strength rises with the cation in the order Na < Mg < Ca < Ba, so the barium salt forms the strongest protective film. Barium and overbased barium sulfonates became the established standard for rust-preventive and slushing oils because the barium sulfonate groups adsorb tightly onto steel, copper and aluminium, build a dense hydrophobic layer, and displace the water and sweat films that initiate electrochemical corrosion.
Unlike the sodium grade, which is an emulsifier, B50 is demulsifying — it resists emulsification and lets oil and water separate, which is what rust-preventive, sealing and circulating oils require. Its protective performance is documented on the data sheet by a passing ASTM D1748 humidity-cabinet result (copper sheet rating A, brass sheet rating 1).
How Barium Petroleum Sulfonate Works
Dense hydrophobic film
The polar barium-sulfonate head adsorbs strongly on steel, copper and aluminium and the non-polar tail packs into a tight, water-impervious monolayer — the strongest film of the sulfonate cations.
Water & sweat displacement
The film displaces existing moisture and fingerprint/sweat residues from the metal and blocks re-wetting, inhibiting the electrochemical corrosion that needs water and oxygen.
Demulsibility
The divalent barium cation resists emulsification, so the additive lets water separate out of the oil — keeping rust-preventive and sealing oils free of trapped water and suited to long-term protection.
Salt-fog & humidity resistance
The barium sulfonate film resists moisture, salt fog and salt water; on the data sheet it passes the ASTM D1748 humidity cabinet (Cu sheet A, brass sheet 1) for durable, long-term sealing protection.
Applications
CheMost-B50 is used as the rust-inhibitor component in formulations targeting the duties below, wherever the strongest sulfonate film and demulsibility are wanted:
Rust-preventive & slushing oils
The core application — long-term anti-rust and sealing oils for machinery, bearings, gauges and stored parts, where the dense barium film and salt-fog resistance protect through extended storage.
Inter-process & sealing oils
Short-term protection during processing, transport and storage, and thick-film sealing oils for outdoor or harsh-environment equipment.
Lubricant & metalworking oils
Dual-purpose rust protection in gear oils, hydraulic oils and greases, and enhanced anti-rust performance in cutting and stamping oils where demulsibility is preferred over an emulsifier.
Finished-oil performance approvals belong to the fully formulated lubricant or rust-preventive fluid, not to an individual additive component. Barium additives are subject to tightening regional controls; CheMost can provide regulatory documentation support on request.
Treat Rate
The data sheet specifies the product but not a per-application dosage, so the figure below is indicative, derived from the target system and our formulating experience — confirm the final level for your formulation.
First-order estimate. In rust-preventive, slushing and sealing oils, barium petroleum sulfonate is typically dosed in the region of 2–10%, trimmed to the salt-fog / humidity-cabinet target and often blended with a neutral sodium or calcium sulfonate and an oxidate or petrolatum for thick-film systems.
The barium grade is normally the film-strength component of a rust-preventive blend: a sodium sulfonate manages any emulsion duty while B50 supplies the durable, demulsifying protective layer. The exact level depends on the required protection period, the base oil and the rest of the rust-preventive package.
Treat rates are indicative, not fixed dosages. CheMost can provide formulation and treat-rate support on request.
Formulating With B50 — Complementary Additives
Barium petroleum sulfonate supplies the strongest sulfonate rust film; a complete rust-preventive or sealing-oil formulation pairs it with additives that cover emulsion duty, alkaline reserve and storage stability:
Sodium petroleum sulfonate
Where a formulation also needs emulsion compatibility (water-extendable or soluble systems), the sodium grade provides emulsification while B50 supplies film strength — the classic neutral-plus sulfonate blend.
Dinonylnaphthalene sulfonates (DNNS)
Barium and calcium DNNS add high-performance rust protection and water displacement, reinforcing the petroleum-sulfonate film in severe-duty preventive oils.
Overbased calcium sulfonate
Supplies an alkaline reserve that neutralises acidic corrosion by-products; combining petroleum oxidates with overbased calcium sulfonate is a known route to improved lubricity and corrosion protection.
Antioxidants
For long-storage sealing and slushing oils, antioxidants slow oil oxidation so the protective film and the oil carrier survive extended outdoor exposure.
The CheMost Sulfonate Rust-Inhibitor Family
Sulfonate rust inhibitors are distinguished by their cation (rust-film strength Na < Mg < Ca < Ba) and by whether they emulsify or demulsify. B50 (this page) is the strongest film, demulsifying grade:
| Product | Cation | Behaviour | Best for |
|---|---|---|---|
| Barium petroleum sulfonate (B50) | Ba (divalent) | Demulsifying, strongest film | Rust-preventive, slushing & sealing oils |
| Sodium petroleum sulfonate | Na (monovalent) | Emulsifying, emulsion-stable | Soluble/semi-synthetic metalworking fluids |
| Calcium DNNS (barium-free) | Ca (divalent) | High-performance, barium-free | Modern RP oils avoiding barium |
| Barium DNNS (overbased) | Ba (overbased) | Alkaline reserve + rust film | Severe-duty preventive coatings |
Documentation, Qualification & Regulatory Support
Standard documentation — Certificate of Analysis (COA, per shipment), Technical Data Sheet (TDS) and Safety Data Sheet (SDS, GHS/CLP) — is provided. The full TDS is available on request rather than as a public download. Additional support is available on request:
Regulatory documentation
REACH, TSCA and country-specific market-registration documentation support available on request — relevant given tightening controls on barium additives.
Third-party inspection
SGS / Intertek / BV pre-shipment inspection can be arranged on request.
Custom grades & packaging
Custom grades and packaging — metal drum, IBC, ISO tank.
Formulation support
Treat-rate and rust-preventive formulation guidance from our technical team.
Packaging & Supply
CheMost-B50 is stocked and shipped worldwide, with a typical lead time of 1–15 days and a 36-month shelf life at ambient temperature. Samples and quotations are answered within 12 hours.
Packaging
200 kg metal drum · 1000 kg IBC tank.
Minimum order
1 drum or 1 IBC — no minimum order value.
Incoterms
FOB · CIF · EXW, to suit your freight arrangement.
Loading ports
All major Chinese ports.
Frequently Asked Questions
What is barium petroleum sulfonate used for?
It is the barium salt of natural petroleum sulfonic acids (CAS 61790-48-5), used as a film-forming rust inhibitor in rust-preventive oils, slushing and sealing oils, greases and dual-purpose lubricant/anti-rust formulations. The barium sulfonate film is the strongest of the sulfonate cations and displaces water and sweat from the metal surface.
What is the difference between barium and sodium petroleum sulfonate?
Rust-film strength rises with the cation (Na < Mg < Ca < Ba), so barium gives the strongest film. Just as important, barium sulfonate is demulsifying (resists emulsification) while sodium sulfonate is an emulsifier. Barium is therefore used in rust-preventive and slushing oils where oil-water separation is wanted; sodium is used in soluble metalworking fluids where a stable emulsion is wanted.
Does CheMost-B50 pass a humidity-cabinet rust test?
Yes — the data sheet reports an ASTM D1748 humidity-cabinet result of copper sheet rating A and brass sheet rating 1, alongside 7.8% barium, 53% barium sulfonate, a flash point of 200 °C, moisture 0.3% and mechanical impurities 0.03%. These are the typical values from the TDS, provided for reference.
Is barium petroleum sulfonate being phased out?
Barium-containing additives face tightening regional regulatory controls, and many formulators are evaluating barium-free alternatives such as calcium DNNS for new work. CheMost supplies both the barium grade and barium-free calcium DNNS, and can provide REACH/TSCA and market-registration documentation support on request.
How is it supplied, and how fast can I get a sample?
It is supplied in 200 kg metal drums and 1000 kg IBC tanks with a 36-month shelf life, and shipped worldwide. As a manufacturer and sourcing partner (Est. 2013), CheMost answers sample and quotation requests within 12 hours.