A sunscreen or foundation brief that only says “add a dispersant” is not a sample request. Polyhydroxystearic Acid is one INCI: a polymer of hydroxystearic acid, sold here as a yellow liquid, CAS 27924-99-8. It goes into the oil phase. It is not a UV filter, and it is not Stearic Acid.
Two other searches land on the wrong molecule. Polyhydroxy acid, the PHA family, is a leave-on acid question. Polyisobutene is a different polymer, with its own safety thread. Neither name fills this purchase order. The split from the fatty acid is Polyhydroxystearic Acid vs Stearic Acid in a Dispersion.
What the INCI is locking
The International Cosmetic Ingredient Dictionary lists Polyhydroxystearic Acid as a non-surfactant dispersing agent. CIR’s 2023 assessment uses the same function and defines it as a polymer of hydroxystearic acid, with CAS 27924-99-8 and CAS 58128-22-6 both attached to the name. A supplier description in that file calls one grade a neat, vegetable-derived polymeric ester, yellow and viscous at room temperature, with a terminal hydroxy and a terminal carboxy group.
Write the INCI you will print. If the regulatory pack needs a CAS line, use 27924-99-8 unless the COA in front of you prints 58128-22-6. Do not pick a number from a monomer. 12-Hydroxystearic acid is the repeating unit’s parent acid. It is not this liquid, and this site has no page for the monomer.
“Structure” searches want that distinction: a polyester of hydroxy stearic units, not a single C18 fatty acid, and not a surfactant micelle. The product page also lists a W/O co-emulsifier role. That is a second job in an oil-continuous cream. It does not turn the liquid into a cleansing surfactant.
How this liquid goes into the oil
The grade on this site is a yellow liquid. Suggested use is 1–5%. Add it to the oil phase. For pigments and mineral filters, mix it with those solids first until the slurry is uniform, then bring in the rest of the oils, esters, or silicones, then emulsify. The page describes that order as the way to cut viscosity so a high-solids dispersion can stay fluid. It is a process note for this liquid, not a finished SPF.
Do not treat 1–5% as the CIR maximum. The 2023 CIR survey reported uses from 0.014% to 14.2%, and the 14.2% figure is in lipsticks. Suntan preparations in that survey were reported at 0.2–0.3%. Moisturizers were reported up to 10%. Those are industry-use observations across many products. They are not the weighing instruction for this drum. Start from the 1–5% window on the product page, then confirm the percent on the TDS against the solids load you actually grind.
One supplier file cited by CIR describes a grade as 100% active and reports a number-average molecular weight around 1243 g/mol and a weight-average around 8243 g/mol. That is that grade’s documentation. It is not printed on this product page. If your spec needs an active-matter line or a molecular-weight window, ask for it on the COA instead of copying the other supplier’s numbers.
Mineral filters are a separate purchase
Searches for polyhydroxystearic acid in sunscreen, in skin care, and in cosmetics are placement questions. The product page positions the liquid for mineral sunscreens and for pigmented creams: it wets titanium dioxide and zinc oxide, and it wets color pigments, so the grind can carry more solids without turning into a paste. The dispersant does not replace the filter. SPF, whitening, and regional UV-filter limits are properties of the filter and the finished chassis.
Titanium Dioxide is on this site as a separate powder, CAS 13463-67-7, insoluble, and meant to be pre-dispersed in the oil or in a pigment grind. Quote it on its own line. Zinc oxide is named on the dispersant page as a mineral filter this liquid can wet. This site has no zinc oxide product page. Do not invent a URL. If the brief needs zinc oxide, source that INCI separately and keep this liquid as the dispersant.
The same page allows the liquid in a W/O cream as a co-emulsifier and stabilizer. That is still an oil-phase charge. It is not a reason to add the polymer to the water phase, and it is not a reason to delete the primary emulsifier.
Trade names and the emulsifiers that share a stem
“Trade name” and “alternative” are the other purchasing forks.
CIR’s unpublished data on this INCI include a grade sold as Pelemol PHS-8. That name is evidence that a commercial liquid can carry this INCI. It is not evidence that the yellow liquid on this page is that brand. Ask the COA for Polyhydroxystearic Acid. Do not write the brand onto the label unless you are buying that brand.
Two materials on this site wear “polyhydroxystearate” in the name and are still different INCIs.
Polyglyceryl-2 Dipolyhydroxystearate is a yellow viscous W/O emulsifier, CAS 121940-62-1, PEG-free. It is not the homopolymer dispersant.
PEG-30 Dipolyhydroxystearate is a brown cream, CAS 70142-34-6. Its page lists both W/O emulsifier and pigment dispersant. A formula can use it when the brief names that INCI. It does not silently replace Polyhydroxystearic Acid, and this polymer does not silently replace the PEG-30 emulsifier. If the brief says “PHSA or the dipolyhydroxystearate, whichever disperses,” send two named lines and let the bench choose. Do not collapse them in the warehouse.
Stearic Acid is the flake people substitute when they only read “stearic.” That mistake is the second article.
What “natural” and “safe” can mean here
A supplier description in the CIR file calls one grade vegetable-derived. “Natural” is still not an INCI and not an assay. The purchasing lines remain the polymer name, the CAS, the yellow liquid, and the oil-phase use.
The CIR panel concluded that Polyhydroxystearic Acid is safe in cosmetics in the present practices of use and concentration described in that assessment. The file includes an occlusive human repeat-insult patch test of the neat ingredient in 51 subjects that was not irritating or sensitizing, and a separate product test at 3.45%. That is a safety-assessment statement. It is not a comedogenic score, not a fungal-acne clearance, and not a side-effect list you can print as “none.” Consumer charts are handled in Polyhydroxystearic Acid Comedogenic Rating: Not an Oil.
What to send before the first sample ships
Put these lines in the message:
- INCI Polyhydroxystearic Acid, not Stearic Acid and not Polyglyceryl-2 Dipolyhydroxystearate
- CAS 27924-99-8, unless your pack specifically requires the alternate 58128-22-6 and the COA shows it
- Form: yellow liquid; confirm whether the lot is neat or diluted
- Use: oil-phase dispersant, slurry with the named pigments or mineral filters before the rest of the oil, starting window 1–5% unless the TDS says otherwise
- The filter or pigment INCI on a separate line, if the grind needs titanium dioxide or zinc oxide
- Bench-sample size, plus COA, SDS, and TDS
Batch documents and a sample are on the product page. Match the sample to the polymer and the liquid form, then scale the slurry. A line that names the dispersant and the solids it has to wet usually returns documents. A line that says only “stearic dispersant” usually returns the wrong solid.
