Two drums can both be labelled Ceteareth-20, match each other on every line of the certificate of analysis, arrive as the same white flake - and still not be interchangeable. The INCI number is an average, not a specification. Ceteareth-2 and Ceteareth-25 share one CAS number (68439-49-6), one INCI stem and one appearance, yet one is an oil-soluble co-emulsifier that will not disperse in water and the other is a water-soluble gelling agent used at 20-30% to build a stiff clear gel. If the EO number is not on the purchase order, neither party has any claim when the batch behaves differently.
That is the most expensive mistake in this family and the only one that leaves no trace on the paperwork you are sent. Ethoxylated fatty alcohols are also the largest single group of emulsifiers in our personal care range, which is why it is worth setting out what actually separates the grades: the EO number first, the alkyl backbone second, and the four specification lines that tell you whether the drum you receive is the one you ordered.
The number in the name is not in the CAS number
Ethoxylated fatty alcohols are made by adding ethylene oxide to a fatty alcohol. The number after the hyphen is the average moles of EO added per molecule, and it is the only figure that predicts how the material behaves. Everything else follows from it:
- Low EO, 2-5 mole. HLB around 5, oil-soluble, liquid or low-melting waxy solid. Used as the lipophilic half of an emulsifier pair, as the W/O emulsifier in cleansing oils, and in make-up where the oil phase must stay external.
- Mid EO, 6-12 mole. HLB 10-13, water-dispersible. Wetting agents, secondary O/W emulsifiers, and the grades that reduce interfacial tension without carrying the whole emulsion.
- High EO, 20-25 mole. HLB 15-16.5, fully water-soluble. Primary O/W emulsifiers, solubilisers for fragrance and lipophilic actives, and - the property that matters most in practice - the grades that co-assemble with a fatty alcohol into a lamellar gel network.
The registry trap is that CAS covers the polymer family, not the individual grade. Oleth-2 and Oleth-20 are both CAS 9004-98-2. Steareth-2 and Steareth-21 are both CAS 9005-00-9. Ceteareth-2 and Ceteareth-25 are both CAS 68439-49-6. Beheneth-10 and Beheneth-25 are both CAS 26636-40-8. The EO number has to be written on the purchase order, the drum label and the incoming goods specification, because the CAS number will not distinguish them.
The EO ladder across our range
Four backbones cover almost every brief. The backbone sets the melt point, the afterfeel and the ceiling on cloud point; the EO number sets everything else. Published HLB values are grade-typical figures - treat them as a route to the right shortlist, then confirm against the supplier's own technical data sheet.
| Grade | CAS No. | HLB | Form at 20 °C | Typical role |
|---|---|---|---|---|
| Laureth-4 | 5274-68-0 | 9.7 | Clear liquid | Wetting, quick-break co-emulsifier, shaving products |
| Oleth-2 | 9004-98-2 | 4.9 | Liquid | W/O co-emulsifier, cleansing oils |
| Oleth-5 | 9004-98-2 | 9.0-9.5 | Liquid | Wetting, secondary emulsifier |
| Oleth-10 | 9004-98-2 | 12.4 | Paste | O/W emulsifier, fragrance solubiliser |
| Oleth-20 | 9004-98-2 | 15.3 | Waxy solid | O/W emulsifier, low-odour solubiliser |
| Steareth-2 | 9005-00-9 | 4.9 | Waxy solid | Low-HLB partner in the classic Steareth pair |
| Steareth-10 | 9005-00-9 | intermediate | Solid | O/W emulsifier for electrolyte-bearing bases |
| Steareth-21 | 9005-00-9 | 15.5 | Flake | High-HLB partner, tolerant of salt and polyols |
| Ceteareth-2 | 68439-49-6 | about 5 | Waxy solid | Low-HLB partner, W/O creams, make-up, sun care |
| Ceteareth-20 | 68439-49-6 | 15.2-15.7 | Flake | Primary O/W workhorse; lamellar gel builder |
| Ceteareth-21 | 68439-49-6 | intermediate | Wax | O/W emulsifier, creams, lotions, sun care |
| Ceteareth-25 | 68439-49-6 | 16.2-16.5 | Powder or wax | Gelling, solubilising, clarity in high-water bases |
| Ceteareth-6 (and) Stearyl Alcohol | 68439-49-6; 112-92-5 | about 11 | Paste | Self-emulsifying wax, single-ingredient cream base |
| Ceteareth-20 (and) Cetearyl Alcohol | 68439-49-6; 67762-27-0 | blend | Flake | Pre-balanced O/W emulsifying wax |
| Beheneth-10 | 26636-40-8 | about 11 | Waxy solid | C22 backbone, mid-HLB |
| Beheneth-20 | 26636-40-8 | 14.7-16.5 | Waxy solid | C22 O/W emulsifier, high melt point |
| Beheneth-25 | 26636-40-8 | about 15.5 | Waxy solid | C22 high-HLB, cloud point above 100 °C |
HLB rises with EO number but not evenly - it climbs steeply up to roughly 10 moles of EO and then flattens, so the grades sitting between the anchors, Steareth-10 and Ceteareth-21, have to be specified from the supplier's own figure rather than interpolated between their neighbours. At the top of the C16-18 ladder, Ceteareth-20 published values spread from 15.2 to 15.7 depending on supplier, which is already enough to move a marginal emulsion across the stability line.
Look next at Beheneth-20: suppliers publish HLB values from 14.7 to 16.5 for the same INCI name, because "20 EO" is an average and the distribution around that average is set by the reactor and the catalyst. For a C22 emulsifier carrying a high-water lotion, that gap is the difference between a product that holds for three years and one that creams in six months. It is the clearest argument in this family for buying on a technical data sheet plus a batch COA rather than on a name.
Cloud point: the number that decides storage stability
Nonionic ethoxylates show inverse solubility - they dissolve better cold than hot. As temperature rises the polyethylene oxide chain progressively dehydrates, the micelles aggregate and the solution turns cloudy. That temperature is the cloud point, and it sets the ceiling for storage, transport and processing rather than the performance of the emulsion at room temperature.
| Grade | Cloud point | Method as published |
|---|---|---|
| Ceteareth-15 | 70-74 °C | 5% sodium chloride solution |
| Ceteareth-20 | 85-92 °C | 5% sodium chloride solution |
| Ceteareth-25 | 88-95 °C | 5% sodium chloride solution |
| Ceteareth-25 | 78-80 °C | 1 g in 100 ml of 10% sodium chloride solution |
| Ceteareth-30 | 91-94 °C | 5% sodium chloride solution |
| Oleth-20 | about 90 °C | aqueous |
| Beheneth-25 | above 100 °C | 1% aqueous |
Three things follow from that table, and all three affect what you put on the specification sheet.
- Cloud point climbs with EO number, and with chain length. Moving from Ceteareth-15 to Ceteareth-25 buys roughly 15 °C of headroom. Moving from the C16-18 ladder to the C22 backbone buys more still - Beheneth-25 is listed above 100 °C in water, which is why it is chosen for hot-fill processes and for markets where a container can sit at 50 °C on a quay.
- Electrolytes depress the cloud point. Salts salt the surfactant out. A Ceteareth-20 reading 85-92 °C in 5% sodium chloride may read far lower in a real base carrying 2% salt, 20% glycerin and a pigment load. Test turbidity in the finished base, not in water, and treat the water-phase cloud point as an upper bound only.
- The method changes the number more than the grade does. The same Ceteareth-25 INCI is published at 78-80 °C by one supplier and 88-95 °C by another purely because one reports in 10% sodium chloride and the other in 5%. Never compare cloud point figures from two suppliers without reading the method line - and never let a customer compare them either.
The gel phase, and how to get past it
High-EO grades share one processing defect that causes more production incidents than any other in this family. Added to water at ambient temperature, they pass through a gel phase on the way to solution: a stiff, clear, immobile mass that stalls the stirrer, blinds transfer lines and cannot be pumped. The material has not failed and the batch is not lost, but the line stops until it is cleared.
The workaround is standard practice in plants that run these grades every day:
- Heat the water phase to about 75 °C, above the melting point of the solid grade, before any surfactant goes in.
- Melt the surfactant in a separate vessel - flake and powder grades ship as hard blocks and need a heating cabinet or drum blanket rather than a hot-water hose.
- Add the molten surfactant to the hot water under high shear, so the mixture passes through the gel window instead of sitting in it.
- Cool gradually to about 40 °C with continuous low-shear agitation, then hold for maturation before measuring viscosity.
The same gel, made deliberately, is a finished product rather than a defect. Ceteareth-20 at 20-30% in water forms a stiff, clear, ringing gel - the basis of the heavy-hold hair gels and edge-control products, and a reminder that in this family concentration can change the physical state, not just the strength of the effect.
Why the low-EO and high-EO grades are bought as a pair
The single most useful habit in this family is to stop treating a grade as a product in its own right and start treating it as one half of a pair. Steareth-2 with Steareth-21. Ceteareth-2 with Ceteareth-20. Oleth-2 with Oleth-20. The high-EO grade drags oil into water and sterically stabilises the droplets; the low-EO partner sits in the oil phase and lowers interfacial tension from the other side.
More importantly, the low-EO or mid-EO grade plus an added fatty alcohol such as cetearyl alcohol self-assembles into a lamellar gel network - ordered liquid-crystal bilayers in the continuous water phase. That network does two jobs at once: it thickens the external phase, giving the cream its body and its shear-thinning application feel, and it forms a mechanical barrier against droplet coalescence, which is why it stabilises an emulsion that no single emulsifier would hold. This is also why a cream thickens visibly as it cools: the network is still assembling after the homogeniser stops.
The EO number controls the switch. Up to roughly 10 moles of EO the C16-18 chain packs into ordered bilayer crystals at useful concentrations and builds viscosity; at 20 moles and above the molecule is too hydrophilic to crystallise that way, so it emulsifies cleanly but thickens little. That is the real reason a Ceteareth-20 formulation almost always carries cetearyl alcohol with it, and why swapping the fatty alcohol out to reduce cost produces a thin, short-lived lotion instead of a cream.
| Application | Typical system | Use level |
|---|---|---|
| Light lotion | High-EO grade + cetearyl alcohol | 2-3% + 2-3% |
| Medium-body cream | High-EO grade + cetearyl alcohol | 3-4% + 3-5% |
| Rich cream or butter | High-EO grade + cetearyl alcohol or glyceryl stearate | 4-5% + 4-6% |
| Self-emulsifying Steareth pair | Steareth-2 with Steareth-21 | 1-5% total |
| Fragrance solubiliser | Oleth-20 alone or with Oleth-10 | 1-2% per 1% fragrance |
| Heavy-hold hair gel | Ceteareth-20 in water | 20-30% |
Choosing the backbone
- C12 - Laureth-4. The lowest melt point in the range and the best wetter. At HLB 9.7 it is a co-emulsifier rather than a stand-alone O/W primary, and it is the grade to reach for in quick-break emulsions, shaving products and anything that must spread instantly.
- C18:1 - the Oleth series. Unsaturated, so it stays liquid up to Oleth-5 and gives a lower melt point and lighter spreading than the saturated ladder. The trade-off is a measurable iodine value and a shorter oxidative shelf life: specify and monitor odour, and keep opaque packaging. Oleth-20 is the low-odour grade of choice for fragrance solubilisation.
- C16-18 - the Ceteareth series. The industry default and the best-documented lamellar builder. Saturated, solid from 20 EO upward, and the backbone behind the pre-blended emulsifying waxes in our range. If a brief does not specify a backbone, this is almost always the right answer.
- C22 - the Beheneth series. The highest melt point of the four. The same EO ladder on a longer chain buys a higher cloud point, a firmer gel network and a richer, more occlusive afterfeel - the reason Beheneth-25 appears where a formulation has to survive hot filling or a tropical warehouse.
Specification and procurement checklist
- Hydroxyl value, mg KOH/g. This is the QC handle on the EO number and the most useful single line on the COA. Ceteareth-20 is typically 46-52, Steareth-21 44-61, Oleth-20 40-65. A hydroxyl value outside the band means the average EO count has drifted, and the HLB has drifted with it - which will show up in your customer's viscosity, not in the drum.
- Cloud point, with the method quoted. A number without the method is not a specification. Require the salt concentration and the sample preparation to be stated on the COA.
- 1,4-Dioxane and residual ethylene oxide. Ethoxylation generates 1,4-dioxane as a byproduct. It is removed by vacuum stripping at the end of the reaction, not by formulation, so it is a supplier property and not something you can fix downstream. The EU SCCS concluded that trace 1,4-dioxane at 10 ppm or below in a finished cosmetic is safe; China's Safety and Technical Standards for Cosmetics limits it to 30 mg/kg; New York State moved to 10 ppm in cosmetics and 2 ppm in household cleaners from 2022, stepping down again in 2023; ASEAN harmonised at 25 ppm in 2020 and 10 ppm in 2023. Put the limit and the test method on the purchase order and ask for the batch figure, not the generic one.
- Diethylene glycol and free PEG content. Both are markers of a reactor that was not tightly controlled, and high free PEG depresses emulsifying efficiency at the same dose.
- Colour, APHA or Hazen. The earliest visible signal of thermal damage during stripping, and directly visible in a white cream.
- Moisture. Typically 0.5-1.0% maximum. Water carried into a solid flake grade shifts the effective HLB and seeds microbial problems in the finished product.
- Free fatty alcohol. High residual alcohol crystallises in the finished emulsion; it shows up as graininess and as a drop in gloss.
- pH of a 1% aqueous dispersion. Typically 5.0-8.0. State the dilution method, because the figure moves with it.
- Feedstock origin and certification. The same INCI exists in palm, other vegetable, animal and petrochemical versions. If the brand makes a sustainability or halal claim, the declaration has to come with the batch, because the name on the drum does not discriminate between them.
Selection quick reference
Classic white O/W cream that has to hold for three years? Ceteareth-20 at 2-4% with cetearyl alcohol - or the Ceteareth-20 and cetearyl alcohol blend if you want one line on the label. Base carrying 2% salt or a heavy pigment load? Move up the ladder: Steareth-21 or Ceteareth-25 rather than the mid-HLB grades, and turbidity-test in the real base. Cream that will be shipped and stored hot? C22 backbone: Beheneth-25, cloud point above 100 °C in water. Cleansing oil or W/O cream? Ceteareth-2, Steareth-2 or Oleth-2 at 2-5% as the lipophilic half. Fragrance that will not dissolve? Oleth-20, and pair it with Oleth-10 for the documented synergy. Stiff clear hair gel? Ceteareth-20 at 20-30% in water, made cold and deliberately. Formulation that must be PEG-free? This class is not the answer - an ester-linked or glucoside emulsifier is. Batch gelled in the mixing vessel? Water was too cold; heat to 75 °C and re-run. Lotion thins out after a few weeks? Check whether the fatty alcohol co-emulsifier is still in the formula before you change the emulsifier.
Shanghai Better Chemical supplies the ethoxylated fatty alcohol range - Laureth-4 (CAS 5274-68-0), the Oleth series Oleth-2, Oleth-5, Oleth-10 and Oleth-20 (CAS 9004-98-2), the Steareth series Steareth-2, Steareth-10 and Steareth-21 (CAS 9005-00-9), the Ceteareth series Ceteareth-2, Ceteareth-20, Ceteareth-21 and Ceteareth-25 (CAS 68439-49-6), the Beheneth series Beheneth-10, Beheneth-20 and Beheneth-25 (CAS 26636-40-8), and the pre-blended emulsifying waxes Ceteareth-6 (and) Stearyl Alcohol (CAS 68439-49-6; 112-92-5) and Ceteareth-20 (and) Cetearyl Alcohol (CAS 68439-49-6; 67762-27-0). We also carry the co-emulsifiers and thickeners these systems are built around - cetearyl alcohol C16-18 (CAS 67762-27-0), glyceryl stearate (CAS 31566-31-1), Glycereth-26 (CAS 31694-55-0) and xanthan gum (CAS 11138-66-2). Every batch ships with a COA covering hydroxyl value, cloud point with method, pH, moisture, colour and 1,4-dioxane, plus TDS, MSDS and samples for line trials. Send us the oil phase, the target pH, the electrolyte load and the storage climate, and we will confirm which grade holds it and quote against current lead times.