Short answer
Choose SCI when high-active powders, flakes, granules or noodles are needed for syndet bars and opaque cleansing formats. Consider SLMI when an 80–82% flake or approximately 32% liquid grade and greater clear-liquid flexibility fit the formulation. The two are not one-to-one substitutes; water content and process design must be recalculated.
Product overview
Sodium Cocoyl Isethionate (SCI)
A cocoyl isethionate commonly supplied as high-active solids and selected paste grades for syndet bars and opaque cleansing systems.
Sodium Lauroyl Methyl Isethionate (SLMI)
A lauroyl methyl isethionate supplied in cited examples as approximately 80–82% flakes or a 32% liquid for clear and opaque cleansing systems.
Technical comparison
| Selection factor | SCI | SLMI |
|---|---|---|
| Surfactant family | Cocoyl isethionate | Lauroyl methyl isethionate |
| Published active matter | 50% paste and 78%, 80% or 85% solid examples | Approximately 80–82% flakes and 32% liquid examples |
| Appearance / form | Powder, flakes, granules, noodles or paste | Waxy flakes or clear pale-yellow liquid in cited guides |
| Mildness | Widely used in mild syndet formats; validate the final formula | Used in mild clear and opaque systems; validate the final formula |
| Foaming | Dense cleansing foam; performance depends on process and blend | Foam and after-feel depend on grade and co-surfactants |
| Solubility / processing | Solid grades often need heat, shear and controlled addition | Liquid grade supports easier dosing; flakes still require suitable incorporation |
| Published pH guidance | Typically 6–8 for cited non-soap systems | Approximately 4.8–8.5 in cited supplier guides |
| Clarity | Primarily opaque liquids and solid bars | Published for both clear and opaque liquid systems |
| Typical applications | Syndet and combo bars, facial cleansing, shampoo, body wash and opaque liquids | Clear or opaque facial cleansers, shampoo, body wash, cream cleansers and selected solid formats |
Advantages and limitations
SCI
Advantages: Multiple high-active solid forms and established fit for syndet bars.
Limitations: Dissolution and handling can be more demanding; clear liquid systems are not its main fit.
SLMI
Advantages: Solid and liquid grade options with published clear-system use and a lower pH starting range.
Limitations: Liquid and flake grades have very different water and active content; availability and exact specification must be confirmed.
Which ingredient should formulators choose?
Choose by finished-product architecture. SCI is a logical starting point for classic syndet bars and opaque concentrates; SLMI is attractive when a clear liquid or easier liquid dosing is required.
For solid formats, compare bar hardness, extrusion or stamping behavior, cracking, wear rate and lather. For liquids, compare clarity, low-temperature stability, viscosity and preservation.
Technical considerations before sampling
Request active matter, pH, free fatty acid, sodium isethionate or related salts, water, particle form, color, odor and preservative as applicable.
Do not treat published supplier examples as universal specifications. Confirm current grade-specific TDS, SDS, COA and recommended process.
Frequently asked questions
Is SLMI a liquid version of SCI?
No. SLMI is a different isethionate chemistry. A liquid SLMI grade is not simply diluted SCI.
Which is better for a syndet bar?
SCI is the established starting point for many syndet bars, while SLMI can also be evaluated depending on structure and processing.
Which is better for a clear liquid cleanser?
The cited SLMI family offers a clearer route because liquid grades are published for clear systems. The complete formula still determines clarity.
Can SCI and SLMI be blended?
Potentially, but recalculate active matter and water, then validate processing, texture, foam and stability.