Back to Ingredient Dictionary
Common Name(s): Fatty acid or acid blend,soap formulation precursor,emollient conditioner
CAS Number: N/a
DESCRIPTION
What It Does: Provides fatty acid emolliency and soap precursor activity.
Why It's Used: Fatty acid emollient/soap precursor โ fatty acids provide skin conditioning in free form and form classical soaps on neutralisation with alkali, providing the oldest cleansing chemistry known.
How It Works: Mixed fatty acid blend. free acid: emollient, barrier. naoh/koh neutralisation โ soap. saponification: classic soap-making chemistry. emollient: free acid sc integration. conditioning. traditional ingredient.
Typically Found In: Soap formulation,emollient products
TECHNICAL DETAILS
Primary Category: Active ingredient โ cosmetic active
Secondary Functions: Skin conditioning
Application Areas:
Facial Skincare
Body Care
Hair Care
Beard Care
Color Cosmetics (Makeup)
Dietary/Oral Supplements
Typical Concentration Range: 0.5%โ20%
SOURCING & ETHICS
Vegan Status: No - animal-derived
Halal Status: Conditional - bee-derived; widely held permissible, confirm certifier stance
Source Notes: Commercially produced for cosmetic use. verify vegan/halal status with supplier. [audit 2026-07-29 rev2: bee-derived; permissibility widely accepted but fatwa varies by jurisdiction. determination requires shariah-panel sign-off.]
SKIN COMPATIBILITY
Irritancy Rating: 1/5 โ very low
Comedogenicity Rating: 0/5 โ non-comedogenic
Sensitivity Concerns: Well-tolerated by most skin types.
Safe for Sensitive Skin: Yes
SAFETY & COMPATIBILITY
Safety Profile: Good safety profile at recommended concentrations. ewg score: 1โ2.
Works Well With: Standard skincare actives
Avoid Combining With: No known significant incompatibilities
SCIENTIFIC NOTE
Fatty acid soap ionisation ph sensitivity: free fatty acids (rcooh) form soaps (rcoo-) above their pka (~4.5-5.0). at skin ph 5.5, fatty acid soaps partially ionise providing a natural buffering that moderates soap harshness. in the soap transition zone (ph 5-7), the equilibrium between rcooh (non-irritating) and rcoo- (cleansing) provides simultaneous mild cleansing and skin compatibility โ the natural soap buffering explaining why fatty acid-based cleansers at slightly acidic ph are gentler than fully alkaline formulations.
Last Verified: 2026-03-12
Primary Sources: Cosing database,fatty acid soap ionisation ph review