Stearic Acid

Description

Stearic acid is a saturated fatty acid with an 18-carbon chain, typically appearing as a white, waxy solid. Its name comes from the Greek word “stear,” which means tallow, reflecting its common source. Stearic acid is one of the most common fatty acids in nature, found in both animal and vegetable fats, though it is more abundant in animal fats like beef tallow and lard. It’s also a major component of cocoa and shea butter.

stearic acid is available in different grades, each designed for specific industrial or commercial applications. The grades vary primarily in purity, free fatty acid content, iodine value, and source (animal or vegetable origin).

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Basic Chemical Information

Property	Value
Chemical formula	C₁₈H₃₆O₂
Molar mass	284.48 g/mol
Appearance	White, waxy solid
Odor	Mild, fatty or odorless
Density (20 °C)	0.9408 g/cm³
Density (70 °C)	0.847 g/cm³
Melting point	69.3 °C
Boiling point	361 °C (decomposes)
Solubility in water	Very low (~0.0029 g/100 g at 20 °C)
Solubility in organic solvents	Soluble in ethanol, acetone, chloroform, toluene, and hexane

 

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Common Grades of Stearic Acid

Commercial Grade: Purity: ~40–60% stearic acid (rest mostly palmitic acid)

Applications:Rubber processing,Candles,Plastics and PVC lubricants,Textile sizing

Triple Pressed Grade: Purity: ≥90% (combination of stearic and palmitic acids) Color: White, low color number (high-quality)

Applications:Cosmetics and personal care products (soaps, creams, lotions)Pharmaceuticals (ointments, excipients)Food additives (with food-grade certification)

Often made from vegetable-based sources (e.g., palm oil)

 Purity: >95% stearic acid , Low odor, high consistency

Applications:High-end cosmetics,Pharmaceuticals, Food industry (as an emulsifier or additive)

Complies with USP/NF, BP, or FCC standards, depending on certification

Pharmaceutical Grade / USP Grade : Purity: ≥98%

Conforms to:United States Pharmacopeia (USP), British Pharmacopoeia (BP)

Applications:Tablet formulations, Controlled drug release systems, Medical ointments and creams

Food Grade(Regulatory Status: Approved by FDA, EFSA, or local food safety authorities)

Applications:Food additives (emulsifiers, binders)Chewing gum base, Dietary supplements. Must be free of harmful contaminants and meet microbiological standards

Technical Grade-Lower purity  May contain higher levels of unsaponifiable matter or impurities

Applications:Industrial manufacturing (e.g., greases, polishes, wax blends)Lubricants

Source Types

Vegetable-based (palm, coconut): Preferred for vegan, cosmetic, and food-grade products.

Animal-based (tallow-derived): Less common now but still used in some industrial applications.

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Uses of Stearic Acid

Stearic acid is a versatile ingredient with a wide range of industrial and consumer applications due to its unique properties as a lubricant, thickener, emulsifier, and surfactant.

1. Soaps and Cosmetics: Stearic acid is a fundamental component in many personal care products. It’s used in soaps and detergents to help create a rich lather and to harden the product. In lotions, creams, and shaving foams, it acts as a thickener and emulsifier, helping to blend oil and water components and giving the product a smooth, creamy texture. It also has emollient properties that help to soften the skin.
2. Candles: It’s used as a hardening agent in candles, which raises the melting point of the wax. This results in a slower-burning, longer-lasting candle that holds its shape better and drips less.
3. Plastics and Rubber: In plastics, stearic acid serves as a lubricant and a stabilizer. In rubber production, it acts as an activator, helping to speed up the vulcanization process (the chemical process that makes rubber more durable and elastic).
4. Industrial Applications: It is used as a release agent in the production of molds and castings, preventing materials from sticking to the mold. It is also used in lubricants, metal polishes, and as a negative plate additive in the manufacturing of lead-acid batteries.
5. Food: Stearic acid is naturally present in many foods and is also used as a food additive to improve texture and stability in products like hard candies, baked goods, and frozen dairy products.