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Hydroxystearic Acid is the INCI and trade name of 12-hydroxyoctadecanoic acid (12-HSA, CAS No 106-14-9, C18H36O3), a castor-oil-derived hydroxy fatty acid that combines the long saturated chain of stearic acid with an extra hydroxyl group, and that is used as a consistency builder, oil structurant, co-emulsifier and soap-forming fatty acid in personal care, lubricants, coatings and specialty chemistry.
The hydroxy fatty acid stands out among fatty acids because the hydroxyl group on carbon 12 lets the molecules link to each other through an additional row of hydrogen bonds, so that even small amounts of Hydroxystearic Acid can harden waxes, stiffen sticks and turn liquid oils into self-supporting gels.
The castor-derived structurant can be used as the free acid, as a soap formed directly in the batch with an alkali, or as the raw material for derivatives such as metal stearates, esters and polyesters, which makes one ingredient useful across very different product categories.
CAS No: 106-14-9
EC No: 203-366-1
Molecular formula: C18H36O3
Molecular weight: 300.48 g/mol
INCI name: Hydroxystearic Acid
Form: Flakes, beads or powder
Color: White to pale yellow
Melting range: approx. 72–80 °C
Saponification value: approx. 180–192 mg KOH/g
Solubility: Insoluble in water, soluble in hot oils and alcohols
COMMON PRODUCT & CHEMICAL NAMES OF HYDROXYSTEARIC ACID:
Hydroxystearic Acid, 12-Hydroxystearic Acid, 12-Hydroxy Stearic Acid, 12-HSA, 12-Hydroxyoctadecanoic Acid, Octadecanoic Acid, 12-hydroxy-, Stearic Acid, 12-hydroxy-, DL-12-Hydroxystearic Acid,Hydroxystearic Acid Flakes, Hydroxystearic Acid Cosmetic Grade, Hydroxystearic Acid Technical Grade, Hydrofol Acid 200, Loxiol G 21, Ceroxin GL, Barolub FTO, Cerit Fac 3
In cosmetic ingredient lists, the substance always appears as Hydroxystearic Acid, the official INCI name. In lubricant and chemical catalogues, the same product is more often called 12-hydroxystearic acid or 12-HSA, and in regulatory databases it is registered as 12-hydroxyoctadecanoic acid or "octadecanoic acid, 12-hydroxy-". Names such as Hydrofol Acid 200, Loxiol G 21, Ceroxin GL, Barolub FTO and Cerit Fac 3 are trade names of individual producers.
The general term "hydroxystearic acid" can in principle refer to any stearic acid carrying one hydroxyl group. Other positional isomers exist, for example 10-hydroxystearic acid (10-HSA, CAS 638-26-6) and 9-hydroxystearic acid, which are different substances with different properties. When Hydroxystearic Acid is ordered, the CAS number 106-14-9 confirms that the 12-hydroxy isomer from castor oil is meant.
WHAT IS HYDROXYSTEARIC ACID?
The hydroxylated fatty acid is a fatty acid with 18 carbon atoms in a straight saturated chain. The first carbon belongs to the carboxylic acid group, and carbon 12 carries a hydroxyl group. Chemically it is 12-hydroxyoctadecanoic acid.
The hydroxy fatty acid does not occur in large amounts in nature. It is made from castor oil, whose main fatty acid, ricinoleic acid, is an unsaturated 12-hydroxy fatty acid. Hydrogenating castor oil saturates the double bond and produces hydrogenated castor oil, a hard wax. Splitting this wax with water under heat and pressure (or by saponification and acidification) releases Hydroxystearic Acid and glycerin.
Commercial Hydroxystearic Acid is a natural-based technical product rather than a single pure molecule. Because castor oil also contains small amounts of oleic, linoleic, palmitic and stearic acids, and because hydrogenation can partly remove hydroxyl groups, typical grades contain Hydroxystearic Acid as the main component together with stearic acid and minor fatty acids. Specifications therefore focus on hydroxyl value, acid value, saponification value, iodine value, color and melting range.
Several grades are on the market. Technical flakes are used for greases and industrial applications. Refined, lighter-colored grades with low odor are offered for cosmetics. High-purity material is supplied for laboratory and analytical purposes.
For a cosmetic chemist, Hydroxystearic Acid is first of all a structuring fatty acid. It gives body to creams and lotions together with fatty alcohols, raises the melting point and firmness of sticks and lip products, and helps keep pigments evenly distributed in color cosmetics. When neutralized with a base such as triethanolamine or sodium hydroxide during emulsion making, Hydroxystearic Acid forms a soap that works as an oil-in-water emulsifier.
For a lubricant producer, Hydroxystearic Acid is the fatty acid behind lithium and calcium 12-hydroxystearate soaps, the thickeners of the most common multipurpose greases. For coating, ink and plastics producers, it is a rheology aid, dispersing agent, lubricant and building block for esters and metal soaps.
Because Hydroxystearic Acid is derived from castor oil, a non-edible vegetable oil, it is often chosen as a renewable alternative to petroleum-based waxes and thickeners.
In finished products, Hydroxystearic Acid helps create firmer, more temperature-stable sticks and balms, creamier emulsions, greases that stay in place, and coatings with improved flow control.
Typical evaluation areas include skin and body creams, cleansing bars, shaving and cleansing creams, deodorant and antiperspirant sticks, lipsticks, eye and lip pencils, hair waxes, sunscreen sticks, multipurpose and complex greases, solvent-borne coatings, printing inks, polishes and wax compounds.
CAS NO, EC / EINECS NO AND CHEMICAL IDENTIFICATION OF HYDROXYSTEARIC ACID
PRODUCT NAME: HYDROXYSTEARIC ACID
Common abbreviation: 12-HSA
Chemical name: 12-Hydroxyoctadecanoic acid
INCI name: Hydroxystearic Acid
CAS No: 106-14-9
EC / EINECS No: 203-366-1
Molecular formula: C18H36O3
Molecular weight: 300.48 g/mol
Chemical class: Saturated hydroxy fatty acid (C18)
Main functions: Consistency builder, oil structurant, co-emulsifier and soap-forming fatty acid, pigment dispersing aid, grease thickener precursor, chemical intermediate
The CAS number confirms the identity of Hydroxystearic Acid but not its quality. Hydroxyl value, stearic acid content and color can vary between producers and grades, and these differences become visible in stick hardness, gel strength and grease yield.
The castor-derived structurant is listed in the EU CosIng inventory under its INCI name, has been assessed by the Cosmetic Ingredient Review (CIR) expert panel, and is registered under REACH in the European Union.
MOLECULAR STRUCTURE OF HYDROXYSTEARIC ACID AND WHY IT MATTERS
The hydroxylated fatty acid can be drawn as CH3(CH2)5–CHOH–(CH2)10–COOH. Three features of this structure explain how it behaves in formulations.
THE SATURATED CHAIN
All carbon–carbon bonds are single bonds. The hydroxy fatty acid therefore resists oxidation and rancidity much better than unsaturated fatty acids, and it gives white to pale, stable products.
THE CARBOXYLIC ACID HEAD
The acid group can pair with another acid group, react with bases to form soaps, or react with alcohols and amines to form esters and amides. This is what makes Hydroxystearic Acid a soap former and a chemical building block.
THE MID-CHAIN HYDROXYL GROUP
The hydroxyl group on carbon 12 is the key difference from stearic acid. It forms hydrogen bonds with hydroxyl groups of neighboring molecules, creating long ordered chains in the crystal. As a result, Hydroxystearic Acid crystallizes into fibers instead of flat plates, melts at a higher temperature than stearic acid and is somewhat more polar. Fiber-shaped crystals are excellent at trapping oil, which explains the gelling and thickening ability of Hydroxystearic Acid and its soaps.
The carbon bearing the hydroxyl group is chiral. Castor-oil-based Hydroxystearic Acid keeps the natural (R)-configuration of ricinoleic acid, and this optically active form is known to give stronger and more regular fibrous structures than racemic material.
PHYSICAL AND CHEMICAL PROPERTIES OF HYDROXYSTEARIC ACID
GENERAL TECHNICAL SPECIFICATIONS:
PHYSICAL APPEARANCE: WHITE TO PALE YELLOW FLAKES, BEADS OR POWDER
Odor: Mild, fatty or almost odorless
Chemical character: Saturated hydroxy fatty acid, weakly acidic
Molecular formula: C18H36O3
Molecular weight: 300.48 g/mol
CAS No: 106-14-9
EC / EINECS No: 203-366-1
Acid value: Approx. 175–185 mg KOH/g
Saponification value: Approx. 180–192 mg KOH/g
Hydroxyl value: Approx. 150–165 mg KOH/g
Iodine value: Typically below approx. 5 g I2/100 g
Color: Typically Gardner 7 max. for technical grades, lighter for cosmetic grades
Melting range: Approx. 72–80 °C
Flash point: Above approx. 210 °C
Water solubility: Insoluble
Solubility: Soluble in hot vegetable and mineral oils, esters, ethanol and many organic solvents
Stability: Stable under normal storage conditions
In practice, the melting behavior of Hydroxystearic Acid is a direct indicator of quality. Lower hydroxyl content and higher stearic acid content usually lower the melting range and weaken the structure that Hydroxystearic Acid builds in oils.
Saponification value and acid value are needed to calculate the amount of alkali required when Hydroxystearic Acid is neutralized in emulsions or converted into soap in greases. Color and odor are especially important for cosmetic and white-colored products.
The figures above summarize typical supplier data and are for guidance only. For the specification of the Hydroxystearic Acid grade currently supplied, please contact Ataman Kimya.
HOW DOES HYDROXYSTEARIC ACID BUILD STRUCTURE IN FORMULATIONS?
IN ANHYDROUS PRODUCTS
When Hydroxystearic Acid is melted into oils and waxes and the mixture cools, it crystallizes into fine fibers that interweave with wax crystals. This network increases hardness, reduces oil sweating and raises the softening temperature of sticks and balms. In some oils, Hydroxystearic Acid alone can form transparent or translucent gels at a few percent.
IN EMULSIONS
In the oil phase of creams and lotions, Hydroxystearic Acid behaves like a high-melting fatty acid and contributes to viscosity and a richer texture. When part of it is neutralized, the resulting soap sits at the oil–water interface and stabilizes the emulsion. The combination of free acid and soap creates a lamellar, creamy structure similar to classic stearate creams, but with a slightly different skin feel and higher heat stability.
IN CLEANSING PRODUCTS
As a soap, Hydroxystearic Acid contributes to cleansing and foaming in bars and cleansing creams, and the free acid adds creaminess and hardness.
IN GREASES
Converted to lithium or calcium soap in base oil, Hydroxystearic Acid forms fibrous soap crystals that hold the oil and give grease its consistency and high dropping point.
IN COATINGS AND INKS
The polar head and hydroxyl group anchor to pigment surfaces, while the hydrocarbon chain extends into the binder. This supports wetting and dispersion, derived structures can also reduce settling and sagging.
MAIN FUNCTIONS OF HYDROXYSTEARIC ACID:
CONSISTENCY BUILDER IN CREAMS AND LOTIONS
Hardening and structuring agent in sticks, balms and pencils
Oil gelling agent
Co-emulsifier and soap-forming fatty acid
Cleansing and foaming contribution in soaps
Pigment wetting and dispersing aid
Precursor of lithium and calcium grease thickeners
Building block for esters, amides, polyesters and metal soaps
HYDROXYSTEARIC ACID IN SKIN CARE, MAKEUP AND HAIR CARE
Personal care is a key market for refined grades of Hydroxystearic Acid.
Creams, lotions and body butters: Hydroxystearic Acid is added to the hot oil phase as a consistency factor and, when partly neutralized, as an emulsifier. It can replace part of stearic acid to give firmer, more heat-stable textures.
Cleansing bars and cleansing creams: As a soap-forming fatty acid, Hydroxystearic Acid adds hardness and creaminess to the lather.
Deodorant and antiperspirant sticks: Hydroxystearic Acid is used with fatty alcohols and hydrogenated castor oil to obtain firm sticks with good pay-off and reduced breakage.
Lipsticks, lip balms and pencils: Hydroxystearic Acid adjusts hardness, melting point and pigment dispersion.
Sun care sticks: It helps keep oil-soluble UV filters and emollients in a firm, stable stick.
Hair waxes and pomades: It gives hold and structure to anhydrous styling products.
When formulating with Hydroxystearic Acid, the melting temperature of the oil phase should be high enough (typically above 80 °C) to dissolve it completely. Cooling rate influences crystal size, and therefore hardness and appearance. A cosmetic-grade raw material with low color and odor should be used, and the final product must be assessed under the cosmetic regulation of the target market.
HYDROXYSTEARIC ACID IN GREASES AND TECHNICAL APPLICATIONS
Lithium and calcium greases: Hydroxystearic Acid is saponified with lithium hydroxide or calcium hydroxide directly in base oil to produce the thickener of multipurpose and water-resistant greases. With complexing acids, it is also used in lithium complex greases for higher temperatures.
Coatings and paints: Hydroxystearic Acid and its derivatives contribute to rheology control and pigment dispersion in solvent-borne systems.
Printing inks: It improves pigment wetting and flow.
Polishes and wax compounds: It modifies hardness, gloss and melting behavior.
Plastics and rubber: Hydroxystearic Acid and its metal soaps act as lubricants and release agents.
Chemical synthesis: Hydroxystearic Acid is used to produce methyl 12-hydroxystearate, polyhydroxystearic acid dispersants, PEG hydroxystearates and various esters and amides.
IN WHICH SECTORS IS HYDROXYSTEARIC ACID USED?
MAIN AREAS OF USE:
SKIN CARE AND BODY CARE
Color cosmetics and lip products
Deodorants and antiperspirants
Hair styling products
Soaps and cleansing products
Lubricating greases
Paints and coatings
Printing inks
Polishes and wax compounds
Plastics and rubber processing
Specialty chemical and oleochemical derivatives
Cosmetic producers look mainly for light color, low odor, consistent melting range and reliable regulatory documentation. Grease producers focus on hydroxyl value, acid value and batch-to-batch consistency. Coating and ink producers pay attention to compatibility and dispersing performance.
IS HYDROXYSTEARIC ACID USED IN COSMETIC, FOOD, AND PHARMACEUTICAL APPLICATIONS?
Cosmetics: Yes. The castor-derived structurant is an established cosmetic ingredient listed in CosIng. It has been reviewed by the CIR expert panel. Cosmetic grades with suitable purity, color and odor should be used, and the safety of the final formulation must be assessed by the responsible person.
Food: Hydroxystearic Acid is not an approved food additive and has no E number. Some of its derivatives have specific, limited permissions in food contact materials under US FDA regulations. Lubricants intended for incidental food contact require specifically formulated and registered products.
Pharmaceuticals: Hydroxystearic Acid itself is mainly used as a raw material, its ethoxylated derivative, macrogol 15 hydroxystearate, is a pharmacopoeial solubilizer used in medicinal products. Analytical reference standards of Hydroxystearic Acid are also available.
Technical grades are designed for industrial use and should not be used in cosmetic, food or pharmaceutical products.
WHICH PROBLEMS CAN HYDROXYSTEARIC ACID HELP SOLVE?
SOFT OR UNSTABLE STICKS
Sticks that break, bend or soften in hot climates can be reinforced with Hydroxystearic Acid, which raises the melting point and strengthens the crystal network.
OIL SWEATING IN ANHYDROUS PRODUCTS
Oil droplets appearing on the surface of lipsticks or balms indicate a weak structure. The hydroxylated fatty acid can bind the oil more effectively.
THIN EMULSIONS
Creams that are too thin or lose viscosity at elevated temperature can gain body from Hydroxystearic Acid used as a consistency factor or as an in-situ soap.
PIGMENT AGGLOMERATION
Uneven color in makeup or inks may come from poorly wetted pigments. Hydroxystearic Acid supports pigment wetting and dispersion.
GREASE SOFTENING AND OIL BLEEDING
In greases, Hydroxystearic Acid-based soaps provide a stable fiber network that resists softening and limits oil bleeding.
Each of these effects should be confirmed in the actual formulation, because results depend on the oils, waxes, emulsifiers and processing conditions used.
THINGS TO CONSIDER WHEN USING HYDROXYSTEARIC ACID
The hydroxy fatty acid is easy to handle, but several factors determine whether it delivers the expected structure.
SELECT A GRADE THAT MATCHES THE APPLICATION: COSMETIC GRADE FOR PERSONAL CARE, TECHNICAL GRADE FOR GREASES AND INDUSTRIAL USE.
Melt Hydroxystearic Acid completely before cooling, undissolved particles lead to gritty textures and weak gels.
Control the cooling rate, because fast and slow cooling produce different crystal sizes and hardness.
When neutralizing in emulsions, calculate the alkali from the acid value and check the final pH.
Consider interactions with other fatty acids, fatty alcohols and waxes, which can strengthen or weaken the network.
Check color and odor stability of cosmetic products after storage at elevated temperature.
Avoid long holding times at high temperature, which can darken the material.
Minimize dust generation when handling powder and keep ignition sources away.
Store away from strong oxidizing agents and strong bases.
According to supplier safety data sheets, Hydroxystearic Acid is not classified as a hazardous substance under GHS. Fine dust can, however, form combustible dust–air mixtures and may cause mechanical irritation of the eyes. Molten material can cause burns. Safety glasses, gloves and dust control are recommended during handling.
INITIAL FORMULATION APPROACHES FOR HYDROXYSTEARIC ACID
The examples below illustrate how Hydroxystearic Acid can be evaluated in the laboratory. They are starting points only, not finished commercial formulas, and must be adjusted and tested for stability, performance, compatibility and safety in each case.
The percentage compositions added below are illustrative laboratory starting mixtures (% w/w), not validated commercial recipes. Each totals 100 % on the stated basis, confirm ingredient grades, compatibility and suitability, and optimise processing and stability.
EXAMPLE 1: HYDROXYSTEARIC ACID AS PARTIAL REPLACEMENT FOR STEARIC ACID IN A TEA-SOAP CREAM
Objective: To compare the texture, viscosity and heat stability of a classic triethanolamine-stearate cream when part of the stearic acid is replaced by Hydroxystearic Acid.
INITIAL COMPONENTS:
Stearic acid: approx. 10, 8, 6 and 4 %
Hydroxystearic Acid: approx. 0, 2, 4 and 6 % (total fatty acid kept constant)
Cetyl alcohol: approx. 1–2 %
Emollient oil or ester: approx. 5–8 %
Glycerin: approx. 3–5 %
Triethanolamine: calculated to neutralize part of the total fatty acid
Preservative: according to supplier recommendation
Water: to 100 %
APPLICATION APPROACH:
The fatty acids, cetyl alcohol and emollient are melted together at about 80–85 °C until clear.
Water, glycerin and triethanolamine are heated separately to the same temperature.
The oil phase is added to the water phase under stirring and homogenized.
The cream is cooled under slow stirring, and the preservative is added at a suitable temperature.
pH, viscosity, appearance and texture are measured after 24 hours and after storage at different temperatures.
The level of Hydroxystearic Acid that gives the desired body and heat stability is selected.
ILLUSTRATIVE INITIAL COMPONENTS FOR THE 4 % HYDROXYSTEARIC ACID TRIAL (% W/W)
Stearic acid: 6.00 %
Hydroxystearic Acid: 4.00 %
Cetyl alcohol: 1.50 %
Emollient oil or ester: 6.00 %
Glycerin: 4.00 %
Triethanolamine: 1.00 %
Preservative: 0.80 %
Water: 76.70 %
Total: 100.00 %
The triethanolamine and preservative amounts are illustrative placeholders, calculate the neutralisation level from actual acid values, confirm the selected preservative requirements and establish final pH. For the other acid ratios, keep total fatty acid at 10 % and rebalance water after any alkali adjustment.
EXAMPLE 2: HYDROXYSTEARIC ACID IN A PIGMENTED LIP BALM
Objective: To evaluate the effect of Hydroxystearic Acid on hardness, oil sweating and pigment distribution in a lip balm.
INITIAL APPROACH:
Hydroxystearic Acid: approx. 0, 2, 4 and 6 %
Candelilla or beeswax: approx. 15–20 %, adjusted to keep total structurant comparable
Castor oil and light esters: balance of the formula
Pigment or pigment paste: approx. 1–3 %, kept constant
Antioxidant: approx. 0.1–0.5 %
APPLICATION APPROACH:
Waxes, Hydroxystearic Acid and oils are melted together at about 85 °C.
The pigment is dispersed into the melt with sufficient shear.
The melt is poured into molds and cooled under controlled conditions.
Hardness, breakage resistance, surface appearance, sweating after storage at elevated temperature and color uniformity are evaluated.
The formulation with the best balance of glide and stability is selected.
ILLUSTRATIVE INITIAL COMPONENTS FOR THE 4 % HYDROXYSTEARIC ACID TRIAL (% W/W)
Hydroxystearic Acid: 4.00 %
Candelilla or beeswax: 16.00 %
Castor oil: 50.00 %
Light ester: 27.80 %
Pigment or pigment paste: 2.00 %
Antioxidant: 0.20 %
Total: 100.00 %
This keeps total acid plus wax at 20 %. For the 0, 2 and 6 % acid trials, use respectively 20, 18 and 14 % wax, the final wax level extends the initial screening range to maintain comparable total structurant. Confirm the antioxidant type and pigment suitability for the target lip product.
EXAMPLE 3: CALCIUM 12-HYDROXYSTEARATE WATER-RESISTANT GREASE
Objective: To prepare a laboratory anhydrous calcium grease with Hydroxystearic Acid and evaluate its consistency and water resistance.
INITIAL APPROACH:
Hydroxystearic Acid: approx. 8–12 % of the final grease
Calcium hydroxide: stoichiometric amount calculated from the acid value
Mineral base oil (e.g. ISO VG 150–320): balance
Small amount of water for saponification, removed afterwards
Antioxidant and rust inhibitor: as required
APPLICATION APPROACH:
HYDROXYSTEARIC ACID IS MELTED IN PART OF THE BASE OIL.
Calcium hydroxide is added as a slurry, and the saponification is completed under stirring and heating.
Water is removed, and the batch is heated to dissolve the soap, then cooled while the remaining oil is added.
Additives are incorporated at lower temperature, and the grease is milled.
Cone penetration, dropping point, water washout and mechanical stability are measured.
Caustic materials, hot oil and steam must be handled with suitable protective equipment.
ILLUSTRATIVE INITIAL REACTION CHARGE (% W/W)
Hydroxystearic Acid: 10.00 %
Calcium hydroxide: 1.19 %
Mineral base oil: 86.31 %
Water for saponification: 2.00 %
Antioxidant: 0.20 %
Rust inhibitor: 0.30 %
Total: 100.00 %
Calculate the calcium hydroxide requirement from the actual acid value and raw-material purity before use, the illustrative amount must be corrected accordingly, with base oil rebalanced to 100 %. Water is removed during processing, so this is an initial charge rather than the final anhydrous grease composition.
HYDROXYSTEARIC ACID SIMILAR PRODUCTS AND ALTERNATIVES
HYDROXYSTEARIC ACID AND STEARIC ACID
Both are C18 saturated fatty acids, but stearic acid has no hydroxyl group. Stearic acid is less expensive and is the standard consistency factor in many creams, while Hydroxystearic Acid gives a higher melting range, stronger structuring and greater heat stability.
HYDROXYSTEARIC ACID AND HYDROGENATED CASTOR OIL
Hydrogenated castor oil is the triglyceride of Hydroxystearic Acid. It is a hard wax used in sticks and as a rheology additive, but it is not a free fatty acid and cannot form soaps without saponification.
Hydroxystearic Acid and 10-hydroxystearic acid
10-hydroxystearic acid is a positional isomer produced from oleic acid. It is used in some modern skin care products for different reasons than 12-HSA and is not a substitute in structuring or grease applications.
HYDROXYSTEARIC ACID AND POLYHYDROXYSTEARIC ACID
Polyhydroxystearic acid is a polymer made from Hydroxystearic Acid and is used mainly as a dispersing agent for mineral UV filters and pigments in oils. It is a derivative, not a replacement.
HYDROXYSTEARIC ACID AND OTHER STRUCTURANTS
Waxes (candelilla, carnauba, beeswax, synthetic waxes), fatty alcohols, ethylcellulose, polyamides, silica and organoclays can also build structure in oils. In greases, polyurea, calcium sulfonate complex and clay thickeners are alternatives.
The most suitable choice should be confirmed by laboratory trials in the target formulation.
HOW DOES HYDROXYSTEARIC ACID WORK AT THE MOLECULAR LEVEL?
Hydroxystearic Acid, in commercial practice mainly 12-hydroxystearic acid, is a saturated eighteen-carbon fatty acid with a hydroxyl group on carbon 12. It is usually obtained by hydrogenating castor oil and then hydrolysing the resulting glyceride, so most material retains the (R)-configuration of natural ricinoleic acid. The molecule therefore has two hydrogen-bonding sites, the carboxyl group at one end and the hydroxyl group in the middle of the chain, separated by a long, straight hydrocarbon segment. This arrangement gives it an unusual ability to organise itself into long fibres, which underlies most of its uses.
Self-assembly through two types of hydrogen bonds: In non-polar liquids, the carboxyl groups of two molecules pair up into cyclic dimers. At the same time, the hydroxyl groups on carbon 12 form chains of hydrogen bonds with the hydroxyl groups of neighbouring molecules. The combination of head-to-head dimers and side-by-side hydroxyl chains directs growth strongly along one axis. Instead of growing as plates or compact crystals, 12-hydroxystearic acid builds long, thin fibrils.
Organogels from small amounts: When the acid is dissolved in a hot oil or solvent and then cooled, these fibrils grow and entangle into a three-dimensional network that traps the liquid. Even at low concentrations, this can turn a liquid oil into a gel, making the molecule one of the best-known low-molecular-weight organogelators. The gel is thermoreversible: heating breaks the hydrogen bonds and dissolves the fibres, and cooling rebuilds the network. The chirality of the (R)-form promotes twisted, high-aspect-ratio fibres, racemic material tends to form less effective, more platelet-like crystals.
Soaps and grease thickening: When neutralised with metal hydroxides, the acid forms metal soaps such as lithium, calcium or aluminium 12-hydroxystearate. In lubricating oils, these soaps crystallise into fibres held together by the same hydroxyl hydrogen bonding together with ionic interactions between carboxylate heads and metal ions. The resulting soap fibre network traps base oil and forms a grease. The hydroxyl group strengthens the fibres and raises the dropping point compared with soaps of plain stearic acid, giving greases better high-temperature stability and mechanical resistance.
Structuring and thickening in cosmetics: In sticks, balms and anhydrous products, hydroxystearic acid crystallises in the oil phase and provides firmness and shape stability. In emulsions, it can be partly neutralised in situ to form a soap that acts as an emulsifier, while the remaining free acid crystallises and thickens the oil phase. These two roles together help stabilise creams and give a smooth, non-greasy feel.
Self-condensation and polymeric stabilisers: The molecule carries both an acid and an alcohol group, so it can esterify with itself. Repeated self-condensation gives poly(12-hydroxystearic acid), a polyester with long pendant hydrocarbon chains. When attached to a pigment surface or combined with hydrophilic segments, these chains extend into the surrounding oil and create a steric barrier that keeps particles or droplets apart. This mechanism is used in pigment dispersants for inks and paints and in polymeric water-in-oil emulsifiers.
Lubrication and release: Metal soaps of hydroxystearic acid act as internal and external lubricants in plastics processing. Their carboxylate heads interact with polar sites on polymers or metal surfaces, while the long chains slide easily past each other, reducing friction during extrusion and moulding and improving release from metal tools.
Corrosion and surface protection: On metal surfaces, the carboxyl group can bind to the oxide layer while the hydrocarbon chains pack into a thin hydrophobic film. The additional hydroxyl groups help neighbouring molecules hold together in this layer, improving its cohesion and its ability to keep water away from the metal.
Behaviour in living systems: Ingested 12-hydroxystearic acid is metabolised by fatty acid oxidation pathways, in which the mid-chain hydroxyl group is also processed. Its derivatives in food contact and cosmetic applications are evaluated on this basis.
Gel strength, viscosity and stability depend on concentration, the polarity of the oil or solvent, cooling rate, the degree of neutralisation, the metal ion used and the other ingredients present. Hydroxystearic Acid dosage and process conditions should therefore be confirmed through laboratory trials.
QUALITY CONTROL AND PURCHASING CRITERIA FOR HYDROXYSTEARIC ACID
RECOMMENDED INFORMATION TO REVIEW BEFORE PURCHASING:
GRADE (COSMETIC, TECHNICAL, HIGH PURITY)
Physical form (flakes, beads, powder)
Hydroxyl value
Acid value
Saponification value
Iodine value
Color
Odor
Melting range or titer
Moisture
Fatty acid composition
Residue on ignition
Origin and traceability
Technical Data Sheet (TDS)
Safety Data Sheet (SDS)
Certificate of Analysis (COA)
Batch number and manufacturing date
Packaging type and net weight
Shelf life and storage recommendations
REACH and cosmetic regulatory documentation
For cosmetic use, additional documents such as allergen statements, residual solvent declarations or other regulatory statements may be requested. For grease production, consistent hydroxyl and acid values from batch to batch are the most important purchasing criteria.
STORAGE AND HANDLING OF HYDROXYSTEARIC ACID
HYDROXYSTEARIC ACID SHOULD BE KEPT IN CLOSED PACKAGING IN A DRY, COOL AND WELL-VENTILATED STORAGE AREA, AWAY FROM HEAT SOURCES AND DIRECT SUNLIGHT.
Flakes may cake if exposed to warm conditions for a long time, so pallets should not be stored next to steam lines, heaters or in direct sun.
The product should be separated from strong oxidizing agents and strong bases.
Dust should be kept to a minimum during weighing and charging, and powder handling equipment should be grounded.
Transport: Hydroxystearic Acid is not classified as dangerous goods for transport according to supplier safety data sheets.
Spilled material should be collected with minimal dust formation and placed in suitable containers for reuse or disposal.
SAFETY INFORMATION OF HYDROXYSTEARIC ACID
Hazard classification: Not classified as hazardous under GHS according to supplier safety data sheets. Fine dust may form combustible dust concentrations in air.
Eye contact: Dust may cause mechanical irritation, rinse with water.
Skin contact: Low irritation potential, wash with soap and water. Molten material can cause thermal burns.
Inhalation: Avoid breathing dust, move to fresh air if irritation occurs.
Ingestion: Rinse mouth, obtain medical advice if discomfort occurs.
Fire: Combustible solid. Extinguish with water spray, foam, dry chemical or carbon dioxide. Combustion gives carbon oxides.
Protective equipment: Safety glasses, gloves and dust protection, heat-resistant protection when handling the molten product.
Environment: Do not release large quantities into drains or the environment.
Disposal: According to local regulations.
WHAT SHOULD BE CONSIDERED WHEN BUYING HYDROXYSTEARIC ACID?
BEFORE PURCHASING, THE FOLLOWING INFORMATION SHOULD BE CLARIFIED:
INTENDED APPLICATION AND MARKET (COSMETIC, GREASE, COATING, INK, CHEMICAL SYNTHESIS)
Required grade and physical form
Key specification limits (hydroxyl value, acid value, color, melting range)
Odor requirements for cosmetic use
Required regulatory and quality documents
Quantity and packaging (25 kg bags, big bags)
Delivery schedule
Hydroxystearic Acid prices follow the castor oil market, which depends heavily on harvests in the main producing regions, as well as hydrogenation and energy costs, grade, volume, packaging and logistics.
SUPPLY OF HYDROXYSTEARIC ACID FROM ATAMAN KIMYA
The castor-derived structurant is a versatile castor-oil-based fatty acid used in cosmetics, greases, coatings, inks and specialty chemicals. Choosing the right grade and specification at the beginning saves time in formulation and production.
Ataman Kimya can provide information on Hydroxystearic Acid grades, specifications, packaging options and price quotations.
Current availability, origin and specifications should be confirmed with Ataman Kimya before ordering.
HELPFUL INFORMATION FOR A QUOTATION REQUEST:
APPLICATION AND TARGET MARKET
Required grade and specification
Estimated annual and order quantity
Packaging preference
Documentation requirements
FREQUENTLY ASKED QUESTIONS ABOUT HYDROXYSTEARIC ACID
WHAT IS HYDROXYSTEARIC ACID?
The hydroxylated fatty acid is 12-hydroxyoctadecanoic acid, a saturated C18 fatty acid with a hydroxyl group on carbon 12. It is produced from castor oil and used as a structuring agent, co-emulsifier, soap-forming fatty acid and chemical intermediate.
IS HYDROXYSTEARIC ACID THE SAME AS 12-HYDROXYSTEARIC ACID?
In commercial and cosmetic use, yes. The hydroxy fatty acid is the INCI name of 12-hydroxystearic acid (CAS 106-14-9). Other positional isomers, such as 10-hydroxystearic acid, are different substances.
WHAT IS THE CAS NUMBER OF HYDROXYSTEARIC ACID?
The CAS number is 106-14-9.
WHAT IS THE EC NUMBER OF HYDROXYSTEARIC ACID?
The EC number is 203-366-1.
WHAT IS THE MOLECULAR FORMULA OF HYDROXYSTEARIC ACID?
C18H36O3, with a molecular weight of 300.48 g/mol.
WHAT DOES HYDROXYSTEARIC ACID DO IN COSMETICS?
It builds consistency in creams, hardens and stabilizes sticks and lip products, helps disperse pigments and, when neutralized, acts as an emulsifier.
HOW IS HYDROXYSTEARIC ACID DIFFERENT FROM STEARIC ACID?
The additional hydroxyl group gives Hydroxystearic Acid a higher melting range, stronger structuring ability and better heat stability.
WHERE DOES HYDROXYSTEARIC ACID COME FROM?
It is made from castor oil by hydrogenation followed by splitting of the resulting hydrogenated castor oil.
IS HYDROXYSTEARIC ACID NATURAL?
It is derived from a natural vegetable oil (castor oil) through hydrogenation and hydrolysis.
HOW MUCH HYDROXYSTEARIC ACID IS USED IN COSMETIC PRODUCTS?
Typical levels range from a few percent in creams and lip products to higher amounts in some sticks, the right level depends on the formula and the desired hardness.
IS HYDROXYSTEARIC ACID USED IN GREASES?
Yes. It is the fatty acid used to make lithium and calcium 12-hydroxystearate grease thickeners.
IS HYDROXYSTEARIC ACID SOLUBLE IN WATER?
No. It dissolves in hot oils, esters and alcohols.
WHAT IS THE MELTING RANGE OF HYDROXYSTEARIC ACID?
About 72–80 °C for commercial grades.
IS HYDROXYSTEARIC ACID HAZARDOUS?
It is not classified as hazardous under GHS according to supplier safety data sheets. Dust control is recommended.
DOES HYDROXYSTEARIC ACID HAVE A UN NUMBER?
No. It is not classified as dangerous goods for transport.
CAN HYDROXYSTEARIC ACID BE USED IN FOOD?
No. It is not an approved food additive and has no E number.
WHAT ARE ALTERNATIVES TO HYDROXYSTEARIC ACID?
Stearic acid, hydrogenated castor oil, waxes, fatty alcohols, polyamides and ethylcellulose in cosmetics, polyurea, calcium sulfonate complex and clay thickeners in greases.
HOW SHOULD HYDROXYSTEARIC ACID BE STORED?
In closed packaging in a cool, dry place away from heat, oxidizing agents and strong bases.
WHICH DOCUMENTS SHOULD BE REQUESTED WHEN BUYING HYDROXYSTEARIC ACID?
TDS, SDS, COA and REACH information, plus cosmetic regulatory statements for personal care use.
WHICH SPECIFICATIONS MATTER MOST?
Hydroxyl value, acid value, saponification value, iodine value, color, odor and melting range.
HYDROXYSTEARIC ACID – TECHNICAL SUMMARY
Hydroxystearic Acid (INCI) is 12-hydroxyoctadecanoic acid, CAS 106-14-9, EC 203-366-1, C18H36O3, 300.48 g/mol. It is a white to pale yellow, castor-oil-based saturated hydroxy fatty acid with a melting range of about 72–80 °C.
The hydroxyl group on carbon 12 allows Hydroxystearic Acid to form fibrous crystal networks, which explains its strength as a structuring agent in sticks and oils, its role as a consistency builder and co-emulsifier in creams, and its use as the precursor of lithium and calcium grease soaps.
Commercial Hydroxystearic Acid contains some stearic acid and minor fatty acids, hydroxyl value, acid value, color and melting range define its quality. It should not be confused with stearic acid, hydrogenated castor oil or other hydroxystearic acid isomers such as 10-HSA.
The castor-derived structurant is used in skin care, color cosmetics, deodorants, hair styling, soaps, greases, coatings, inks, polishes, plastics and specialty chemicals.
It is not classified as hazardous under GHS according to supplier safety data sheets and is not regulated for transport, but dust and molten material should be handled with care.
Companies planning to source Hydroxystearic Acid through Ataman Kimya are advised to share their application, grade and specification requirements, quantity and documentation needs to confirm current product, stock, origin, packaging and quotation details.
The hydroxylated fatty acid can be sourced from ATAMAN KİMYA. For further information and supply inquiries about Hydroxystearic Acid, please contact ATAMAN KİMYA.
