Stearic Acid CAS 57-11-4

Stearic Acid – Versatile Emulsifier and Thickener for Cosmetics and Pharmaceuticals

Basic Information

• CAS Number: 57-11-4

• Molecular Formula: C₁₈H₃₆O₂

• Molecular Weight: 284.48 g/mol

• Synonyms: Octadecanoic acid, n-Octadecanoic acid, Stearophanic acid

• Appearance: White waxy solid, flakes, or powder

• Melting Point: 69–70°C

• Solubility: Insoluble in water; soluble in oils and organic solvents

• Storage: Store in a cool, dry place, protected from light and moisture

Overview
Stearic acid is one of the most common saturated fatty acids, widely used in the cosmetic, pharmaceutical, and soap industries. It is derived from natural fats and oils (such as palm oil, coconut oil, and animal tallow) through hydrolysis and purification. Its long hydrophobic carbon chain and polar carboxyl group give it excellent surface-active properties, making it an ideal ingredient for emulsification, thickening, and stabilization of formulations.

Applications

• Cosmetics and personal care: Used in creams, lotions, sunscreens, makeup, and hair care products as an emulsifier, thickener, and stabilizer. Provides a smooth, creamy texture and enhances product spreadability.

• Soap manufacturing: A key component in soap formulations, contributing to hardness, lather stability, and cleansing properties.

• Pharmaceuticals: Used as an excipient in tablets, ointments, and suppositories; acts as a lubricant and emulsifying agent.

• Industrial: Used in rubber, plastics, and coatings as a release agent, lubricant, and stabilizer.

• Food industry: Used as an emulsifier and stabilizer in certain food products (subject to regulations).

Key Benefits

• Provides excellent thickening and stabilizing properties.

• Improves emulsion stability and prevents phase separation.

• Enhances product texture, consistency, and skin feel.

• Acts as a co-emulsifier, helping to form stable oil-in-water (O/W) emulsions.

• Contributes to the hardness and lather stability of soap bars.

• Safe, non-irritating, and widely used in dermatological formulations.

• Compatible with a wide range of cosmetic and pharmaceutical ingredients.

Recommended Use
Typical usage levels range from 1–10% of the formulation, depending on the desired consistency and emulsion stability. For optimal performance, incorporate into the oil phase with heating (60–70°C) before emulsification. Can be combined with other fatty acids, emulsifiers, and thickeners for tailored rheology.

Safety and Handling

• Generally recognized as safe (GRAS) for use in cosmetics, food, and pharmaceuticals at recommended concentrations.

• Low irritation potential; well-tolerated by skin.

• Avoid contact with strong oxidizers and acids.

• Store in a cool, dry place, away from direct sunlight and moisture.

• Use appropriate personal protective equipment (gloves, safety goggles) when handling.

• Shelf life: typically 24–36 months under recommended storage conditions.

Quality Assurance
Each batch is tested for acid value, saponification value, and purity to ensure consistent quality and compliance with cosmetic and pharmaceutical standards.