Sodium Cocoyl Isethionate (SCI)

What is it? A solid, gentle anionic surfactant made from coconut oil.
INCI Sodium Cocoyl Isethionate
Appearance You can buy SCI as a fine powder, a lumpy powder, chips, or noodles/tiny sticks.
Usage rate The CIR has tested it at up to 49.87% in rinse-off applications and 17% in leave-on applications.
Texture It depends on what you buy (see “appearance”).
Scent Characteristically soapy/detergent-y.
Active Surfactant Matter ~84% (always double check with your supplier)
pH 4.5– 6.5 (10% Solution)
Charge Anionic
Solubility Water
Why do we use it in formulations? 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.
Do you need it? If you’re only going to buy one solid, anionic surfactant, I’d recommend this one.
Strengths Wonderful, gentle lather.
Weaknesses The larger shapes can be a pain to melt down.
Alternatives & Substitutions 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).
How to Work with It 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 recipe and heating the two together in a water bath until you have a uniform paste. That paste will dissolve into water.

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!

Storage & Shelf Life Stored somewhere cool, dark, and dry, SCI should last for at least two years.
Tips, Tricks, and Quirks I like to pre-prepare a paste of SCI and Cocamidopropyl Betaine (2 parts SCI to 3 parts Cocamidopropyl Betaine) and store it in the fridge. That way I can skip the dissolving step when I need to include Sodium Cocoyl Isethionate (SCI) in a liquid product.

Watch for SCI that has been blended with stearic acid (INCI will list stearic acid); that isn’t the same product.

Recommended starter amount 250g (0.5lb)
Where to Buy it  Buy it from an online DIY ingredient supplier or Amazon.

Want to compare different surfactants?

Check out my super-useful surfactants table!

 

Some Formulations that Use Sodium Cocoyl Isethionate

Skills

Posted on

November 22, 2018

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