Question 1

What does Steareth-21 do in a cosmetic formula?

Accepted Answer

It is a nonionic emulsifier and solubilizer used to build oil-in-water emulsions and help disperse oils, waxes, and fragrance components into water-based formulas. It also supports texture and emulsion stability in creams, lotions, and cleansers.

Question 2

Is Steareth-21 clean?

Accepted Answer

From a clean-beauty perspective, it is generally well tolerated on skin but receives scrutiny because it is made by ethoxylation, a process that can leave trace ethylene oxide or 1,4-dioxane if purification and testing are weak. Many clean frameworks allow it only with residue controls, while stricter natural standards do not align with it.

Question 3

Is Steareth-21 sustainable?

Accepted Answer

This material is typically synthetic, with a fatty alcohol portion that may come from palm, other vegetable oils, or petrochemical sources, plus an ethoxylated chain usually tied to petrochemical feedstock. It is expected to biodegrade better than silicones or fluorinated materials, but sourcing traceability and process-residue control matter.

Question 4

Is Steareth-21 COSMOS-approved?

Accepted Answer

It is not permitted under COSMOS-natural or COSMOS-organic because the ethoxylation step relies on petrochemical-derived chemistry that the standard excludes. Its Green Chemistry profile is mixed, with useful performance at low levels and likely biodegradability, but less favorable feedstock and residue-management considerations.

Question 5

How does Steareth-21 work chemically?

Accepted Answer

The molecule is a nonionic amphiphile with a long saturated C18 hydrocarbon tail and an average of 21 oxyethylene units, giving it a high HLB around 15.5. It is commonly used around 0.5% to 5%, is broadly stable across typical cosmetic pH ranges, and is often paired with lower-HLB emulsifiers to strengthen oil-in-water systems.