murphyButyl Stearate
AKA: 123-95-5, Butyl octadecanoate, N-Butyl stearate, Octadecanoic acid, Butyl ester, Kesscoflex BS, Kessco BSC, N-Butyl octadecanoate, Butyl octadecylate, Starfol BS-100
Plant-Derived
Emollient
Skin Conditioner
Clean
OriginDerived from stearic acid (a saturated fatty acid) and butanol through esterification synthesis. Produced by chemically combining stearic acid with butyl alcohol under catalytic conditions.
The CIR Expert Panel concluded that the alkyl esters, listed subsequently, are safe in the present practices of use and concentration described in this safety assessment when formulated to be non-irritating.
Solubility Insoluble in water; soluble in ethanol; very soluble in acetone
Formula
C22H44O2
Mol. Weight
340.60
CAS #
123-95-5
Form
Liquid
Skin Types
●all-skin-types, gentle
Best For
Dryness
Pregnancy & Breastfeeding Safe
Yes
Functions
Skin Conditioning
A catch-all term for ingredients that improve how skin looks and feels — softer, smoother, more supple. The workhorse behind most moisturizers.
Emollient
Fills in the tiny cracks between skin cells to make everything feel smooth and soft. The "silky finish" ingredient.
Locks In Moisture
The paper trail
🔬Peer-reviewed1 paper →
⚖️Regulatory1 listing →
🛡️Safety-assessed3 reviews →
Counts, not a verdict. A listing isn't a study. The trail, you decide.
EWG
1
CIR
Safe as used
Pregnancy
Yes
CIR Safety Findings
Not Phototoxic
Human test and Product formulation test found no phototoxicity in the CIR safety assessment (CIR 189 and 623)
Not an Eye Irritant
1 study / 1 not irritating (CIR 189)
Comedogenic in Testing
Animal test with a comedogenic result in the CIR safety assessment (CIR 189 and 623)
Mixed Skin Irritation Results
10 studies / 6 irritating / 4 not irritating / reactions minimal to moderate (CIR 189 and 623)
Mixed Sensitization Results
4 studies / 1 sensitizing / 3 not sensitizing (CIR 189 and 623)
Concentration Guide
Leave-on0.002–12%
Rinse-off0.0008–2%
0%50%100%
CIR reported use · 2012 survey
Regulatory Agencies
Verified Jun 2026
Data: PubChem · CosIng · EWG · CIR