Glyceryl Stearate: A Workhorse Nonionic Emulsifier

If you've ever wondered why one lotion recipe calls for "glyceryl stearate" and another calls for "glyceryl stearate SE" and treated them as interchangeable, it's worth slowing down. They behave differently in the pot, and mixing them up is one of the more common reasons a first emulsion batch splits.

The plain version: Glyceryl Stearate

Plain glyceryl stearate, INCI name Glyceryl Stearate, carries CAS number 31566-31-1 (note that some suppliers list slightly different CAS numbers depending on purity and isomer mix, since this is a case where a single common name can map to more than one registry number). It's the mono-ester of glycerin and stearic acid, and on its own it is a fairly weak emulsifier. It's nonionic, meaning it has no electrical charge, which makes it compatible with a wide range of other ingredients, including many cationic conditioning agents that ionic emulsifiers would clash with.

Used alone, plain glyceryl stearate mostly functions as a co-emulsifier or an emollient that adds a silky, slightly waxy skin feel. It thickens a formula and contributes to a stable-feeling texture, but it usually cannot hold an oil-in-water emulsion together by itself in a typical lotion at normal use levels.

The self-emulsifying version: Glyceryl Stearate SE

The "SE" stands for self-emulsifying, and this version is a blend, typically glyceryl stearate combined with a small amount of an anionic co-emulsifier such as potassium stearate or sodium stearate (sometimes cetearyl alcohol appears in the mix as well, depending on the supplier). That added anionic component is what gives it real standalone emulsifying power. On an ingredient list, if your supplier's blend contains more than just glyceryl stearate, each component needs to be broken out and listed by its own INCI name at its actual concentration in the finished product, not folded into a single "glyceryl stearate SE" line.

This is the multiply-through-the-blend situation that trips people up on filings generally. If your supplier's SE grade is, say, a blend where the co-emulsifier makes up a meaningful minority of the total, and you're using that blend at a few percent of your total formula, you multiply the blend's use level by each component's percentage within the blend to get the real finished-product concentration of each piece. Get the supplier's spec sheet or safety data sheet and use the actual composition breakdown, since it varies by manufacturer.

Side by side

Property	Glyceryl Stearate (plain)	Glyceryl Stearate SE
INCI name	Glyceryl Stearate	Glyceryl Stearate (plus co-emulsifier INCI names)
Typical CAS	31566-31-1 (verify with supplier)	Blend, no single CAS
Self-emulsifying	No	Yes
Charge	Nonionic	Nonionic base with anionic co-emulsifier
Typical role	Co-emulsifier, emollient, thickener	Primary emulsifier
Typical use level	1 to 5 percent	2 to 6 percent, formula-dependent

Why the distinction matters beyond texture

Getting this right matters for two separate reasons. First, formulation: if you substitute the plain grade where a recipe calls for the SE grade, your emulsion is much more likely to separate, because you've removed the anionic partner that was doing the actual emulsifying work. Second, and this is the compliance angle, if you list your finished product's ingredients as simply "Glyceryl Stearate" when you actually used the SE blend, you've under-reported what's really in the product. Regulators and future formula reviewers rely on the ingredient list reflecting the true composition, and a supplier blend hiding behind a single simplified name is exactly the kind of gap that causes rework later.

Neither grade carries special restrictions on the Cosmetic Ingredient Hotlist at typical cosmetic use levels, and both are common across lotions, creams, and conditioners. The compliance work here isn't about a restriction, it's about accurate naming and concentration math.

A quick habit that saves rework

Whenever you bring in a new emulsifier, pull the supplier's technical data sheet before you finalize your formula, not after. Confirm whether it's a single substance or a blend, get every INCI name in the blend, and note the blend's internal percentages. That single step, done once per ingredient, is what makes a Cosmetic Notification Form accurate on the first pass instead of needing an amendment later.

This is also the kind of detail Cosmetic Comply handles automatically. Feed it your formula and it expands supplier blends like glyceryl stearate SE into their individual INCI components, carries the percentage math through correctly, and has a real reviewer sign off before anything gets filed.