Sodium Cocoyl Isethionate (SCI)

Sodium Cocoyl Isethionate (SCI) is a solid, gentle anionic surfactant made from coconut oil. It is really versatile and one of my favourite surfactants. It is primarily used to create solid cleansers like shampoo bars, but can also be used to make opaque liquid cleansers.

Sodium Cocoyl Isethionate

You can buy SCI as a fine powder, a lumpy powder, chips, or noodles/tiny sticks.

The CIR has concluded that Sodium Cocoyl Isethionate (SCI) is “safe for use in cosmetic formulations at 50% in rinse-off products and at 17% in leave-on products”. (source)

The specific wording regarding what the CIR looked at is: “The greatest concentration of Sodium Cocoyl Isethionate tested as a rinse-off product was 49.87%.” The full report says “In 1993, the Cosmetic Ingredient Review (CIR) published the safety assessment of sodium cocoyl isethionate with the conclusion ‘safe for use in cosmetic formulations at 50% in rinse-off products and at 17% in leave-on products’. These concentration limits were based on the maximum concentrations reported in safety test data at the time.”

From that wording, I interpret that they didn’t find issues with higher usage rates—they simply didn’t check above 49.87% as that was the maximum reported usage at the time.

How much you’ll need in any given formulation depends on a ton of variables. For solid bars I usually start with at least 30% Sodium Cocoyl Isethionate (SCI); for liquid formulations 5–15% is a decent starting point.

It depends on what you buy (see “appearance”).

Characteristically soapy/detergent-y.

~84% (always double check with your supplier as this number can vary)

What is the other ~16%? “Sodium cocoyl isethionate may contain the following impurities: … sodium chloride (0.8% max.), free fatty matter (10% max.), sodium isethionate (5%), free fatty acid (18%), and sodium soap (3%).” (source)

Assuming 49.87% is the maximum active concentration in a formula, that works out to 59.38% of 84% active SCI. I think it’s reasonable to assume the CIR is talking about active SCI concentrations since ASM/impurities can vary between brands/manufactures.

4.5– 6.5 (10% Solution)

Anionic

Sodium Cocoyl Isethionate is slightly water soluble. Its cousin, Sodium Lauroyl Methyl Isethionate (SLMI), is far more water soluble.

It offers beautiful, gentle “lace glove” lather to our products. It’s also naturally acidic, so it helps our end products have a skin-friendly pH with less (or no) adjusting.

It depends on what you want to make! If you primarily want to make shampoo bars and other solid cleansing bars, I highly recommend Sodium Cocoyl Isethionate (SCI).

If you are more interested in foaming bath products (bath salts, bath bombs, bath truffles, etc.), I’d probably choose Sodium Lauryl Sulfoacetate (SLSa) over Sodium Cocoyl Isethionate (SCI) as it’s far more water soluble.

If your primary aim to create liquid surfactant products, I’d choose liquid surfactants and/or solid surfactants that are more water soluble (Sodium Coco Sulfate [SCS], Sodium Lauroyl Methyl Isethionate [SLMI], Sodium Lauryl Sulfoacetate [SLSa]) than Sodium Cocoyl Isethionate (SCI) is.

Wonderful, gentle lather.

Between its poor water solubility and tendency to hydrolyze (break down) in hydrous (liquid) formulation with a pH below 6, causing formulations to become unstable, SCI is best suited to solid/bar formulations.

As a bare minimum you’ll need a different solid anionic surfactant. You’ll also need to watch the active surfactant matter (you may need to use a different quantity of the new surfactant to get the same ASM level in the end product) and the pH of the final product. Keep in mind that most solid anionic surfactants are not as gentle as SCI. Two options to consider would be SLSa and Sodium (C14-16) olefin sulfonate (Bio-Terge AS90).

Wear a dust mask! Inhaling airborne powdered surfactants is unbelievably unpleasant.

If you’re making a solid product you can usually work with the SCI as-is, depending on the format. If you’ve got large flakes and the formulation calls for the powdered version you’ll want to pre-grind it (wear your dust mask!), but the little noodles look really cool in shampoo bars as-is, and the fine powder is very flexible!

If you are making a liquid product with Sodium Cocoyl Isethionate (SCI), it will need to be dissolved in a suitable solvent first. Sodium Cocoyl Isethionate (SCI) does not dissolve readily into water; I once combined some Sodium Cocoyl Isethionate (SCI) with water in a jar, sealed it, and left it for 6 months. It never dissolved. I recommend combining it with the liquid amphoteric surfactant that is likely also present in the formulation and heating the two together in a water bath until you have a uniform paste. That paste will dissolve into water, though it will not make a clear mixture unless the level of SCI is very low.

If you are working with a large amount of this Sodium Cocoyl Isethionate (SCI) + amphoteric surfactant blend you can speed things along by using an immersion blender to get the mixture silky smooth—the low water content means it won’t lather up, but you’ll get a smooth paste very quickly! You can also speed up the process by running your SCI through a coffee grinder before combining it with the liquid amphoteric surfactant—just be sure you are wearing your dust mask!

Hydrous formulations including Sodium Cocoyl Isethionate (SCI) should have a pH of 6–8 or the Sodium Cocoyl Isethionate (SCI) can hydrolyze. I have made more acidic formulations including Sodium Cocoyl Isethionate (SCI); with small batches that were finished quickly it can be ok, but I have also experienced a thick sediment accumulating at the bottom of such formulations after a couple months.

Stored somewhere cool, dark, and dry, SCI should last for at least two years. I’ve had some SCI for upwards of five years and haven’t noticed any difference in appearance or performance.

If the first two or three ingredients in a bar are Sodium Cocoyl Isethionate and stearic acid, that formulation probably uses a version of SCI that has been pre-mixed with stearic acid, like Innospec’s Pureact SNDT-65. “Sold as easily handled flakes, Pureact SNDT-65 produces solid cleansing products with smooth texture and luxurious lather.” Sample cleansing bar formulations using this ingredient use 78–86% Pureact SNDT-65 and are produced using extrusion. Examples include Dove’s Cream Beauty Bathing Bar, Cetaphil’s Gentle Cleansing Bar, Kiehl’s Rare Earth Deep Pore Purifying Concentrated Cleansing Bar, and Avene’s Ultra-Rich Soap-Free Cleansing Bar With Cold Cream.

Stephenson’s Syndopal Solid Premium Shampoo MB (Hydrogenated Vegetable Oil (and) Sodium Cocoyl Isethionate (and) Aqua (and) Polyglyceryl-4 Laurate (and) Glycerin (and) Sodium Cocoyl Glutamate (and) Sodium Chloride (and) Tetrasodium Glutamate Diacetate) is also really popular. Sample formulations made with this base usually use ~95% of it. You’ll probably recognize it by the cluster of Sodium Cocoyl Isethionate, hydrogenated vegetable oil, and Polyglyceryl-4 Laurate; examples include Glossier’s Milky Jelly Cleansing Bar, L’Occitane’s Shea Solid Face Cleanser, Aveda’s Shampure Nurturing Shampoo Bar, Davines’ Momo Shampoo Bar, and Good Molecules’ Cleanse & Clarify Bar.

250g (0.5lb)

 Buy it from an online DIY ingredient supplier.