AOS and SLES can both be considered for a liquid-detergent project, but replacing one acronym with the other is not a formulation decision. A buyer must compare the exact offered grades and then test them in the same finished-product brief. MOS lists sodium alpha-olefin sulfonate (AOS) as liquid and powder catalogue forms and sodium lauryl ether sulfate (SLES) as paste grades. Those entries establish candidates and enquiry routes. They do not demonstrate that either MOS grade will produce better cleaning, foam, viscosity, skin feel or storage stability in a buyer's formula.
Start with the delivered grade, not just two acronyms
AOS is an olefin sulfonate; SLES is an ethoxylated alkyl ether sulfate. Producer product bulletins confirm the distinction for their own materials, while the current MOS pages identify the offered families and forms. This chemistry distinction matters, but neither name is a universal performance ranking. A detergent containing other surfactants, builders, salt, fragrance or preservative can respond differently from a simple aqueous solution.
The supplied form changes the practical comparison. MOS lists AOS/35 and AOS/38 as liquids and AOS/92 as powder; its SLES page lists standard and low-dioxane paste variants. A powder may need a different charging and dissolution procedure from a paste, and the water carried by each delivered material changes the formula balance. Equal kilograms of supplied material are not necessarily equal active-surfactant doses. First obtain the current offered-grade TDS, its active-matter test method and a lot-specific result. Do not treat a catalogue range without a stated method as the measured value of the batch being purchased.
Before asking for a “drop-in” replacement, record the incumbent grade, the finished detergent's intended use, manufacturing sequence, available water, target appearance and the performance or processing problem that needs solving. This brief determines which candidate and which acceptance endpoints belong in a sample trial.
Use a two-stage trial in the actual detergent base
Use the same base formula and process as a reference, not two unrelated supplier demos. At the first stage, prepare small candidates using each grade's verified active basis. Account for the water and other material delivered with each form. Hold the rest of the formulation, mixing order, water source, sample age and measurement method as constant as practicable. A matched-active screen can reveal whether a candidate is worth further work; it cannot prove interchangeability or final use performance.
At the second stage, optimize any salt or other thickener separately for each complete candidate formula while documenting what changed. If one sample receives more salt or has a different water balance, a viscosity difference cannot be assigned to AOS versus SLES alone. Set the measurement temperature, elapsed time after mixing and instrument method before comparing results. A formula can also change on storage, so include the buyer's intended storage check rather than relying only on the fresh beaker.
| Trial stage | Control or record | Decision that stage can support |
|---|---|---|
| Delivered-grade check | Exact grade, physical form, current active method, lot value and charging instruction | Whether a defensible dose and water balance can be calculated |
| Same-base screen | Incumbent formula, co-ingredients, water, mixing sequence, active basis and measurement conditions | Whether each candidate merits full-formula development; not a substitution guarantee |
| Separate formula adjustment | Salt/thickener addition, pH adjustment if relevant, appearance and viscosity method for each candidate | Whether a workable version of each whole formula exists |
| Use and storage qualification | The buyer's cleaning, foam, rinse, appearance and stability endpoints under stated conditions | Whether the final formula meets agreed acceptance criteria |
This is a design for a controlled comparison, not a table of measured MOS results. If the two candidates are prepared at unverified active content or different water conditions, repair the trial before interpreting a winner.
Diagnose viscosity and foam without declaring a winner
If the AOS candidate appears thinner, first ask whether its supplied water content, actual active dose, salt level, temperature and time after mixing match the SLES candidate. If a sample thickens only after extra salt, record the full salt-response sequence; the observation belongs to that finished formula and process, not to a permanent family-level superiority claim. If foam seems different, match the vessel, agitation, water and observation interval, then test the cleaning and rinsing endpoints that the detergent must actually meet. A foam photograph alone cannot establish detergency, mildness or long-term stability.
An early failure can guide the next check. Haze after fragrance addition may point to a compatibility or mixing-order question; viscosity drift after storage may point to composition, temperature or time effects. Neither observation, by itself, proves that one surfactant family is unsuitable. Where a different question is specifically AOS versus non-ethoxylated SLS, the existing AOS versus SLS guide covers that distinct comparison. It does not replace a direct AOS/SLES trial.
Write a purchase specification only after the formula passes
Once a candidate formula meets the agreed use and storage checks, convert the trial into an offered-grade purchase specification. Record the exact AOS or SLES grade, form, agreed active-matter method and tolerance, relevant impurities with their test methods, packaging, batch-document requirement and qualified manufacturing conditions. Ask for the current TDS/SDS and lot COA. A “low-dioxane” SLES catalogue variant is a grade distinction; it does not, by itself, prove that a shipment meets a buyer's impurity limit or that a finished detergent satisfies a regulation. Verify the limit, analytical method and lot result where that criterion matters.
For a useful MOS enquiry, send the current formula's surfactant grade and target use, the candidate AOS or SLES form, water and salt conditions, the acceptance endpoints, intended sample and order quantity, packaging and destination. The AOS product page is the primary route for the AOS option; the SLES product page is the separate route for the ether-sulfate option. Request a documented pilot basis, not a promise that one surfactant is universally better.
Sources: Stepan BIO-TERGE AS-40A product bulletin and Stepan STEOL CS-230 K PLUS product bulletin are cited solely for their own grades' identity and application context. They do not certify any MOS grade or the formula outcomes described here.