PEG-100 Stearate

PEG-100 Stearate (CAS 9004-99-3) is the polyethylene glycol (100 EO) monoester of stearic acid — a hydrophilic, nonionic oil-in-water (O/W) emulsifier widely used across personal care and cosmetics. With a high ethylene-oxide content, it carries a high HLB (~18.8) and almost never works alone. Formulators reach for it as the hydrophilic half of the classic Glyceryl Stearate (and) PEG-100 Stearate self-emulsifying base, where it is paired with low-HLB glyceryl stearate to build stable, easy-to-process O/W creams and lotions.

What PEG-100 Stearate does in a formulation

PEG-100 Stearate is built by esterifying stearic acid, a C18 fatty acid, with polyethylene glycol of roughly 100 ethylene-oxide units. That long EO chain is what makes it strongly water-loving. On its own it is too hydrophilic to emulsify a typical oil phase, so its job is to supply hydrophilic character to a balanced emulsifier system — it pulls the overall HLB up toward the level an O/W emulsion needs.

Pair it with glyceryl stearate (HLB ~3.8) and the combined blend lands near HLB 11, a practical target for emulsifying the non-polar oils and waxes common in skin-care. The two-emulsifier approach is more forgiving than a single surfactant: it tolerates a wider oil-phase range and tends to produce smoother, more stable emulsions. The trade-off is that you are committing to a fixed glyceryl-to-PEG ratio, so if your oil phase is unusually polar or unusually heavy you may still need to adjust co-emulsifiers or stabilizers rather than rely on the pair alone.

Applications

Primary O/W emulsifier and co-emulsifier

The dominant use is as the workhorse emulsifier for lotions, creams, and milks. As the Glyceryl Stearate (and) PEG-100 Stearate system it functions as a self-emulsifying (SE) base — add it to the oil phase, combine the phases hot, and it builds the emulsion with straightforward processing. This is why it is one of the most reached-for O/W systems in cosmetic labs: predictable, easy to scale, and stable across a useful pH window, which makes it a common choice for formulas that include acidic actives such as AHAs and BHAs.

Solubilizer for oils and fragrance

Because of its high hydrophilicity, PEG-100 Stearate also helps carry small amounts of oil-soluble material — light oils, emollient esters, and fragrance — into the water phase. Formulators use it to keep these components evenly dispersed rather than separating out over shelf life.

Texture and viscosity contribution

Beyond emulsifying, the stearate backbone contributes body and a characteristic smooth, cushioned skin-feel. In the SE blend it supports viscosity build without heavily thickening the formula, which gives formulators room to dial in rheology with the rest of the system rather than fighting an over-thick base.

Forms and grades

PEG-100 Stearate and the glyceryl stearate / PEG-100 stearate SE blend are typically supplied as solid flakes, pastilles, or pellets that melt into the oil phase during processing. Two procurement paths are common: the pre-blended Glyceryl Stearate (and) PEG-100 Stearate SE emulsifier, bought as a single ingredient for drop-in formulating, or standalone PEG-100 Stearate for labs that prefer to build and tune their own emulsifier ratio. Confirm INCI composition, blend ratio where applicable, and grade specifics against the supplier’s technical data sheet and Certificate of Analysis for each lot.

Handling

Store in a cool, dry place in closed containers and handle per the Safety Data Sheet, which governs PPE, storage, and incompatibilities. The SDS and CoA are the authoritative source for handling and specification — review them before formulation and scale-up.

Source PEG-100 Stearate in bulk

RawSource sources PEG-100 Stearate (CAS 9004-99-3), and the complete Glyceryl Stearate (and) PEG-100 Stearate self-emulsifying emulsifier system, in bulk for personal-care and cosmetic manufacturers. Tell us your target volume, packaging, and ship-to location and we will return a quote. Request a quote to get started.