SLES vs SLS vs CAPB: Choosing the Right Surfactant

Choosing a surfactant is rarely about finding one “best” molecule. In practice, formulators build a surfactant system — a primary surfactant that does the cleaning, and a secondary surfactant that softens, thickens and stabilises it. Three materials sit at the centre of that decision for most personal- and home-care cleansers: SLES, SLS and cocamidopropyl betaine (CAPB).

What is the difference between SLES, SLS and CAPB?

SLES (sodium laureth sulfate) and SLS (sodium lauryl sulfate) are both anionic primary surfactants derived from fatty alcohols. The practical difference comes from ethoxylation: SLES carries an ethylene-oxide chain that makes it more water-soluble and generally milder, while SLS is more aggressive, foams densely and is usually cheaper per kilo of active.

CAPB (cocamidopropyl betaine) is different in kind: it is amphoteric, carrying both a positive and a negative charge depending on pH. That is what lets it act as a secondary surfactant — it pairs with an anionic base to build viscosity, improve foam quality and reduce the irritation potential of the overall system.

When should you choose each one?

Reach for SLES when mildness matters

If the product touches the face, contacts skin for longer, or is positioned as gentle, the extra solubility and lower irritation potential of SLES usually justify its cost. It also responds predictably to salt thickening, which formulators rely on for viscosity control.

Reach for SLS when foam and cost lead

For rinse-off products where dense foam and price are the priorities — many shampoos, dish and hard-surface cleaners — SLS remains a workhorse. It is often blended with SLES rather than used alone.

Add CAPB as the secondary surfactant

In the large majority of cleansers, CAPB (or another amphoteric) is added on top of the anionic base. It is rarely the primary cleaning agent; its value is in making the system milder, thicker and better-foaming.

How sourcing shapes the decision

The formulation answer is only half the picture. The same INCI name can arrive at very different active concentrations, purity grades and price points depending on the manufacturer and origin. That is where an independent distributor adds value: matching the right grade from the right producer to your specification, with the lead time and documentation your market requires.

Berstin supplies SLES, SLS and cocamidopropyl betaine in multiple grades from a curated manufacturer network. Tell us your application, active concentration and destination, and we will respond with technical data, lead times and indicative pricing.