A practical guide to cocamidopropyl betaine, why it is never used alone, how it thickens an anionic base, and how it is supplied, from a US-based distributor.
Cocamidopropyl betaine (CAPB, CAS 61789-40-0) is an amphoteric surfactant derived from coconut oil, supplied as a clear yellow aqueous solution. It is the standard partner to SLES in cleansing bases, where it boosts and stabilises foam, builds viscosity, and cuts the irritation of the anionic system. Stratus Chemical supplies it in drums and totes across the United States.
| Property | Value |
|---|---|
| Chemical name | Cocamidopropyl betaine |
| INCI name | Cocamidopropyl Betaine |
| Synonyms | CAPB, CAB, coco amidopropyl betaine, cocoamidopropyl betaine |
| CAS number | 61789-40-0 |
| EC number | 263-058-8 |
| Molecular formula | C19H38N2O3 |
| Molecular weight | 342.5 g/mol |
| Appearance | Clear yellow liquid |
| Grades supplied | Technical, aqueous solution |
| Packaging | Drums, totes |
| Documentation | COA & SDS provided on request |
The figures below are representative of technical grade cocamidopropyl betaine solution. They are indicative rather than guaranteed: specifications vary by source, grade, and lot, and the certificate of analysis for your material governs.
| Property | Typical value |
|---|---|
| Appearance | Clear yellow liquid |
| pH (5% aqueous) | 4.5 – 6.5 |
| Solids, % | 35.0 – 37.0 |
| Actives, % | 29.7 – 32.2 |
| Sodium chloride, % | 4.8 – 5.3 |
| Viscosity at 25 °C | 17 |
| Pour point, °C | −8 |
| Flash point, °C | Above 94 |
This distinction causes more confusion in CAPB purchasing than any other, and both figures appear on the specification above.
Solids is everything left after the water is removed: the betaine itself plus the sodium chloride and other by-products of the reaction. Actives is the betaine alone, the part that does the work. On this specification solids run 35.0–37.0% while actives run 29.7–32.2%, and the gap between them is largely the 4.8–5.3% sodium chloride.
A product described simply as "35%" is almost always quoting solids. Comparing that against another supplier's actives figure makes the second product look weaker when it may not be. Always establish which basis a quote uses before comparing, and price against actives.
CAPB is made by reacting coconut fatty acids with dimethylaminopropylamine and then with a chloroacetate salt. The result is amphoteric: it carries both a positive and a negative charge on the same molecule, and its net charge shifts with the pH of the system it sits in.
That dual charge is the whole reason it exists commercially. Anionic surfactants such as SLES are cheap and foam well but are relatively harsh, and they do not tolerate cationic ingredients. CAPB is compatible with anionic, nonionic, and cationic systems alike, which makes it the connective tissue of most modern cleansing formulations.
CAPB is a poor primary surfactant. On its own it foams modestly and cleans weakly, and building a base around it would be expensive and disappointing. Its value is entirely in what it does to a system built on something else.
It raises mildness. Anionic surfactants irritate partly by binding to and disrupting skin proteins. CAPB forms mixed micelles with the anionic surfactant, and the resulting larger, less aggressive aggregates interact with skin far less. The effect is real and it is why a well-built SLES and CAPB base is markedly milder than SLES alone at the same total active level.
It builds viscosity. This is the formulator's practical reason for reaching for it. An SLES solution thickens when salt is added, but the response is limited. Add CAPB and the mixed micelles change shape, and the system becomes far more responsive to salt. Most clear shampoos and body washes get their body from this interaction rather than from any added polymer.
It stabilises foam. CAPB does not create much foam by itself but it makes foam last, producing the denser, creamier lather associated with a quality product.
The primary market, typically at 2 to 6% active alongside an SLES primary surfactant. Baby and sensitive-skin products push the ratio further toward CAPB to raise mildness.
Used where mildness is a selling point and where the formulation has to remain gentle with repeated daily use.
Added to hand dishwashing liquids for foam stability and for the skin feel that consumers notice over a sink full of dishes, and to hard-surface cleaners for its tolerance of a wide pH range.
CAPB appears in car wash formulations, in textile processing as a wetting and levelling agent, and in oilfield foaming applications, where its stability across pH and hardness is useful.
| Consideration | What to expect |
|---|---|
| Ratio to primary surfactant | Commonly 1 part CAPB to 3–5 parts anionic active; more CAPB raises mildness and cost |
| Viscosity response | Salt response improves sharply once CAPB is present; adjust salt after the CAPB addition, not before |
| pH of the finished product | Cleansing products are normally finished near skin pH; CAPB is amphoteric and its behaviour changes with pH, so adjust and then check viscosity again |
| Pour point | Around −8 °C; below this the product will not pump, so plan winter storage accordingly |
| Sodium chloride | Contributes to the salt already in the system and affects where the viscosity curve peaks |
How to use the table: the two lines that cause the most trouble in production are salt and pH, and they interact. Because both CAPB and SLES bring chloride with them, and because viscosity rises with salt to a peak and then falls, a base can be thickened past its maximum and end up thinner after adding more salt. Adjust pH first, then approach the target viscosity from below.
Store CAPB in closed original packaging in a cool, ventilated place, protected from freezing and out of direct sunlight. Prolonged heat causes colour drift, which shows up in clear products.
Because it is a water-based surfactant solution containing organic material, CAPB is preserved on supply. Check the preservative system and its shelf life if the material will be held for an extended period, particularly in warm storage.
The concentrate is irritating to eyes and skin. Use the protection specified in the Safety Data Sheet. Spills are slippery and foam heavily if hosed.
Cocamidopropyl betaine is used as a secondary or co-surfactant in shampoos, body washes, facial and hand cleansers, dishwashing liquids, and hard-surface cleaners. Its jobs are boosting and stabilising foam, building viscosity in anionic systems, and reducing the irritancy of primary surfactants such as SLES. It is also used in car care, textile processing, and oilfield foaming applications. Stratus Chemical supplies it in drums and totes across the United States.
The CAS number for cocamidopropyl betaine is 61789-40-0. Its EC number is 263-058-8, its molecular formula is C19H38N2O3, and its molecular weight is approximately 342.5 g/mol. Its INCI name is Cocamidopropyl Betaine and it is commonly abbreviated CAPB or CAB.
Because it is a weak primary surfactant. On its own CAPB foams modestly and cleans poorly, and a base built around it would be expensive and underperforming. Its value comes from what it does to a system built on an anionic surfactant: it forms mixed micelles that are gentler on skin, it makes the system far more responsive to salt so the product thickens properly, and it makes foam denser and longer-lasting. The pairing is the point.
Through its effect on micelle structure. An SLES solution alone thickens only modestly when salt is added. When CAPB is present, the two surfactants form mixed micelles that change shape as salt is added, and the system becomes much more responsive, building viscosity that would otherwise require a separate thickening polymer. Most clear shampoos and body washes get their body from this interaction rather than from an added thickener.
Solids is everything remaining after the water is removed, which includes the betaine plus the sodium chloride and other reaction by-products. Actives is the betaine alone. A typical specification runs solids at 35.0 to 37.0% and actives at 29.7 to 32.2%, with much of the difference accounted for by the 4.8 to 5.3% sodium chloride. A product described simply as "35%" is almost always quoting solids, so establish which basis a quote uses before comparing suppliers and price against actives.
Store CAPB in closed original packaging in a cool, ventilated place, protected from freezing and away from direct sunlight. Prolonged storage at elevated temperature causes colour drift, which is visible in clear formulations. As a water-based solution containing organic material it is supplied preserved, so check the preservative system and shelf life if it will be held for an extended period in warm conditions.
Stratus Chemical supplies cocamidopropyl betaine in drums and totes, as a technical grade aqueous solution, with a certificate of analysis and Safety Data Sheet provided on request. Tell us the actives level you require and the volume, and we will confirm pricing and availability within one business day.
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