CASHEW OIL

Cashew Nut Shell Liquid, also known as CNSL, Cashew Oil, Cashew Nut Shell Oil, Cashew Shell Oil and CAS No. 8007-24-7, is a bio-based raw material distinguished by its natural phenolic structure. It is used particularly in epoxy hardeners (phenalkamines), friction materials, anti-corrosive coatings, marine paints, insulating resins and rubber formulations as a flexibilizer, water-resistance provider and resin modifier.
Cashew Oil, or CNSL for short, forms a structure that is both flexible and hydrophobic during curing thanks to the long aliphatic side chain and phenolic ring in its structure; it is regarded as one of the most effective natural additives for heavy-duty coating systems in terms of water resistance, chemical resistance, surface tolerance and corrosion prevention performance.
Epoxy and resin systems containing Cashew Nut Shell Liquid in their formulations form a hard, impact-absorbing film that is highly resistant to humid conditions, thanks to the reaction of the phenolic structure with epoxy resins or formaldehyde components.
The use of this CNSL-based natural binder modifier in a formulation can provide functional benefits such as increased impact absorption in the final product, reduced internal stresses, improved adhesion to rusty and damp surfaces, and prevention of water penetration after curing.
Cashew Oil exhibits dual reactivity thanks to its central phenolic ring and the 15-carbon unsaturated side chain attached to this ring (cardanol, cardol), establishing a balance of both hardness and high flexibility between polymer chains.
Cashew Nut Shell Liquid reacts with amines and aldehydes to form phenalkamine-type hardeners and, in formulations using Cashew Shell Oil, contributes to low-temperature curing, fast drying and surface tolerance.

Cashew Oil is a functional bio-based raw material used to help reduce problems in coatings such as insufficient flexibility, high moisture sensitivity, embrittlement, weak corrosion resistance and low impact resistance.
CNSL reacts in a controlled manner with resin systems and helps maintain the mechanical flexibility, water resistance and long-term adhesion stability of the coating.
In industrial formulations, it is a functional resin modifier that, thanks to its reactive structure and hydrophobic character, helps keep curing behavior, flexibility properties and corrosion performance at the desired level.
Epoxy and phenolic systems containing Cashew Shell Oil support the development of coatings for the end user that are longer-lasting, unaffected by moisture, and can be reliably applied in harsh marine and industrial environments.

CNSL is an effective natural modifier that can simultaneously support multiple performance properties in coating and composite systems, thanks to its high phenolic reactivity, the flexibility offered by its aliphatic chain, and its excellent compatibility with polymeric resins.
Thanks to its versatile chemical structure and proven corrosion prevention performance, Cashew Nut Shell Liquid helps meet several needs at once — such as flexibility, water resistance, surface tolerance and low-temperature curing — compared with synthetic alternatives that focus on a single property.
It can be evaluated in ship paints, marine structure coatings, brake linings, automotive friction pads, floor coatings and electrical insulating varnishes, and can also be used as a reactive softener in phenolic casting resins and rubber compounds.
While helping the formulator develop moisture-resistant and flexible resin systems, CNSL can provide practical benefits for the applicator, such as excellent adhesion even in areas where surface preparation is difficult and fast drying in harsh weather conditions.

WHAT IS CASHEW OIL (CASHEW NUT SHELL LIQUID)?

Cashew Oil, also called Cashew Nut Shell Oil or Cashew Nut Shell Liquid, CNSL for short, is a natural mixture of phenolic compounds with aliphatic side chains, obtained from the shells of the cashew nut. Cashew Oil is also referred to by names such as CNSL, Cashew Shell Oil, Raw CNSL, Technical CNSL, Cardanol and Cardol. Depending on the processing and refining method, it can be found in different commercial and chemical forms such as Raw CNSL or Distilled Cardanol.
Owing in particular to its phenol content, viscosity, color index, degree of purity, moisture content and density of reactive double bonds, it can exhibit different curing, flexibility and viscosity-reducing behaviors in polymer formulations. Expressions such as CNSL Modifier, Cardanol Resin, Phenalkamine Hardener, Cashew Phenolic Resin and Natural Epoxy Curing Agent are terms that may be encountered in technical and commercial searches. However, these expressions do not all describe the same product in every case. For example, Raw CNSL and Distilled Cardanol, although obtained from the same natural source, are two separate commercial forms with different viscosity, color and chemical purity properties.
Moreover, not all Cashew Oil products on the market have the same physical properties or the same processing behavior. The product's cardanol/cardol ratio, volatile matter content, moisture content, ash content, viscosity and color can significantly change its performance. Therefore, it should not be assumed, based solely on the product name "Cashew Oil" or "CNSL", that products from different manufacturers are technically interchangeable.
C₂₁H₃₂O (the base structure for cardanol) is the representative molecular formula of Cashew Oil components. The central phenolic ring provides high chemical and heat resistance, while the 15-carbon unsaturated side chain at the meta position of the ring imparts high hydrophobicity and flexibility. This structural feature is the basis for CNSL's ability to create pronounced water repellency and impact absorption even at low usage levels.
Cashew Oil can be used in particular for purposes such as imparting flexibility in epoxy systems, producing phenalkamine-type hardeners, serving as a binder in brake linings and friction materials, developing anti-corrosive primers, and acting as a tackifier in rubber compounds. Depending on the application, more specific product definitions such as Raw CNSL, Decarboxylated CNSL or Cardanol may be used.
The performance of Cashew Oil does not depend solely on its natural source. Cardanol content, viscosity, moisture, color, ash content and degree of purity can affect the formulation result. Therefore, two CNSL products sold under the same chemical name may not have the same reactivity, drying time, color stability or film flexibility.

Depending on the quality grade, Cashew Oil can be evaluated in heavy industrial coatings, marine and ship paints, friction linings, floor coating systems, casting resins, the automotive supply industry, electrical insulating varnishes, rubber compounds, adhesives and anti-corrosion primers. Its most common use is in surface-tolerant anti-corrosion coating systems used together with epoxy resins.
Thanks to this hydrophobic reactivity potential in its chemical structure, Cashew Oil, particularly when reacted with formaldehyde and amines, forms phenalkamine hardeners that dry quickly at room temperature and even in damp and cold environments. Defined in the coatings industry by different functional names such as CNSL modifier, cardanol curing agent and cashew resin, this bio-based compound makes it possible to achieve high water resistance and mechanical flexibility at well-balanced usage levels. This hydrophobic polymer structure maximizes the flexibility, impact resistance and scratch resistance of the cured coating film, as well as its corrosion resistance against harsh environmental conditions such as salt water.
Commercially available Cashew Oil products consist of a mixture of cardanol, cardol, anacardic acid and 2-methylcardol components, depending on the extraction and distillation processes. In plants and laboratory formulations, products are generally processed in basic forms: standard Raw CNSL (crude grade), heat-treated Decarboxylated CNSL, and high-purity Distilled Cardanol. Produced as a liquid or viscous with a brown/amber appearance, this natural chemical component may vary in terms of resin compatibility, curing speed and surface wetting depending on technical parameters such as viscosity, phenolic hydroxyl value, moisture content and color. In conclusion, Cashew Nut Shell Liquid is a fundamental bio-based modifier that provides high-durability surface protection and friction performance across a wide range, from marine structures to automotive brake linings.

COMMON PRODUCT AND CHEMICAL NAMES:

Cashew Nut Shell Liquid

Cashew Oil

CNSL

Cashew Nut Shell Oil

Cashew Shell Liquid

Cashew Shell Oil

Cardanol

Cardol

Anacardic Acid

Decarboxylated CNSL

Technical CNSL

Raw CNSL

Distilled Cardanol

Phenalkamine Precursor

CNSL Resin

Cashew Phenolic Resin

Cashew Friction Dust

CNSL Modifier

Bio-based Phenolic Compound

Natural Epoxy Hardener Intermediate

Cashew Curing Agent

CNSL Tackifier

Bio-Polyol Cashew

Some of these names refer to chemical composition, some to the refining stage, and others to the field of use or commercial function. For example, Cardanol denotes a specific phenolic component, while CNSL is the abbreviation for the general source. Decarboxylated CNSL describes the form decarboxylated by heat treatment. Phenalkamine Precursor and CNSL Modifier, on the other hand, are commercial designations referring to the product's function in coatings.
It is important to evaluate the CAS number used for Cashew Nut Shell Liquid together with the product's degree of refinement. While CAS No 8007-24-7 is listed in sources for the general raw CNSL registration, CAS No 37330-39-5 is used as a separate registration for the purified Cardanol form. Therefore, which form the product is in should be checked against the documentation at the time of purchase.

CAS NO, EC / EINECS NO AND CHEMICAL IDENTIFICATION

Product name: Cashew Nut Shell Liquid (Cashew Oil)

Common abbreviation: CNSL

Chemical name: Phenol, 11-[(1E)-1,4-pentadienyl]-2-pentadecyl- (main Cardanol component) / Cashew Nut Shell Liquid

CAS No: 8007-24-7 (Raw/Technical CNSL); 37330-39-5 for Cardanol

EC / EINECS No: 232-355-4

Molecular formula: C₂₁H₃₂O (representative formula of Cardanol)

Molecular weight: ~300.5 g/mol (based on the Cardanol component)

Chemical class: Natural aliphatic-substituted phenol / Bio-based phenolic compound

Main functions: Resin modifier, hydrophobic agent, hardener intermediate, flexibilizer and friction agent

The chemical composition of cardanol, the dominant component of Cashew Nut Shell Liquid, is C₂₁H₃₂O, with a molecular weight of approximately 300.5 g/mol. Since the molecule contains both a reactive phenolic -OH group and a 15-carbon unsaturated side chain, it offers dual reactivity; in commercial products, viscosity and purity may vary depending on the production process.
CAS No 8007-24-7 and EC No 232-355-4 are listed in various official and technical sources for the general CNSL registration. This registration directly covers raw and technically processed products, while a separate CAS registration exists for high-purity Cardanol.
However, using a single identification for Cashew Oil may not be sufficient for every commercial product. Since the cardanol/cardol ratio directly affects viscosity and color stability, the product's exact chemical identity and related technical documents should be checked at the time of purchase.

Cashew Oil in its standard form is not used as a cosmetic, food or pharmaceutical raw material; therefore, there is no INCI name, food additive number or pharmacopoeia definition for the product. The product's field of use is limited to industrial coatings, friction materials and polymer applications.
Rather than a single pure substance, Cashew Oil can be regarded as a natural product that commercially consists mostly of a mixture of cardanol, cardol, 2-methylcardol and polymerized phenolic oligomers. Therefore, depending on the natural source and processing technique, component distribution and purity can change the product's technical performance.

CHEMICAL STRUCTURE AND MOLECULAR PROPERTIES OF CASHEW OIL

Cashew Oil is a natural compound with a benzene ring (phenol) at its center, carrying a long unsaturated hydrocarbon chain of 15 carbon atoms at the meta position of this ring. This special asymmetric structure enables the molecule to exhibit both polar (reactivity of the phenolic group) and non-polar (hydrophobicity of the aliphatic chain) properties.
The phenolic ring is highly prone to reacting with aldehydes and amines, and imparts thermal stability and corrosion resistance. This structure contributes to giving the polymer network formed after curing high chemical resistance and surface adhesion. Compared with classic Bisphenol A or synthetic phenols, the CNSL structure offers extra flexibility and water repellency thanks to its long aliphatic chain.
The unsaturated double bonds in the aliphatic side chain can undergo autoxidation and polymerization with atmospheric oxygen or with agents such as sulfur/peroxides. These double bonds give the molecule high internal flexibility (internal plasticization), counterbalancing the rigidity of the phenolic ring.

The technical performance of Cashew Oil cannot be understood from its natural source alone. Cardanol/cardol ratio, viscosity, phenolic hydroxyl value, moisture content, ash content and color grade are important parameters that determine product behavior.
CNSL can be found in different compositions depending on the extraction method (cold pressing, solvent extraction or heat treatment/roasting). Raw CNSL contains a high proportion of anacardic acid, while technical CNSL decarboxylated by heat treatment is converted predominantly into cardanol and cardol. Separating cardanol by distillation yields lighter-colored, lower-viscosity products.
The molecule's long aliphatic chain structure makes it possible to achieve permanent internal flexibility in rigid epoxy and phenolic resins without the need for externally added plasticizers. This property is one of the main reasons why CNSL increases impact resistance while reducing water permeability in industrial coatings.

PHYSICAL AND CHEMICAL PROPERTIES OF CASHEW OIL

Cashew Oil is generally a viscous liquid with a characteristic odor, dark brown or reddish-brown in color, or dark amber in refined forms. Its physical appearance may vary depending on the extraction method, degree of decarboxylation, level of distillation and commercial grade.

General technical properties:

Physical appearance: Dark brown or amber-colored viscous liquid

Chemical character: Natural mixture of phenolic compounds with aliphatic chains

Molecular formula: C₂₁H₃₂O (Cardanol component)

Molecular weight: ~300.5 g/mol (Cardanol)

CAS No: 8007-24-7 (Raw/Technical CNSL registration)

EC / EINECS No: 232-355-4

Viscosity (25 °C): 150 - 600 cPs depending on grade (lower for distilled forms)

Hydroxyl Value: Varies with purity and cardanol content

Water solubility: Practically insoluble in water; exhibits a highly hydrophobic character

Organic solvents: Readily soluble in aromatic hydrocarbons, alcohols, ketones and esters

Reactivity: Can react with formaldehyde, epoxy, amine, isocyanate and sulfur compounds

Moisture content: Maximum 1% - 2% (should be stated in the specification according to grade)

Ash / Residue content: Depends on the production and refining process

The physical properties of Cashew Oil can vary considerably depending on the product's degree of purification. Raw CNSL shows higher viscosity and darker color, while Distilled Cardanol has lower viscosity and a lighter color, which can offer advantages in sensitive coating applications.
Phenolic hydroxyl value and viscosity are among the most important technical performance parameters of Cashew Oil. These values are used to calculate the correct reaction ratios with formaldehyde or epoxy resins. Two CNSL products with different viscosities, when used at the same ratio, may give different ease of application and different film properties.
Moisture content is important for preventing undesirable side reactions, especially in epoxy and polyurethane reactions. Low moisture content is preferred in high-quality paint and resin systems.
These values are for general technical introduction only; they should not be used as a binding specification for the product to be purchased. Parameters such as viscosity, phenolic OH value, moisture, ash content, color value and cardanol percentage in particular should be checked against the supplier's current TDS and COA documents.

HOW DOES CASHEW OIL WORK AT THE MOLECULAR LEVEL?

The main effect of Cashew Oil in formulations is achieved through the phenolic group bonding to the polymer matrix as a reactive center, and the flexible 15-carbon side chain creating space between polymer chains, forming a hydrophobic shield.
In epoxy and coating formulations, CNSL or its derivative phenalkamine hardener is mixed with epoxy resins, solvents, pigments and fillers. After application, the reaction of the phenolic ring and amine groups with the oxirane rings of the epoxy begins. The long-chain aliphatic structure forms flexible segments within the curing matrix that can move freely but are chemically bonded.
In this reaction, the phenolic ring provides high adhesion and chemical resistance, while the 15-carbon side chain enables the matrix to repel water molecules. Thanks to the hydrophobic blockage in the structure, moisture is prevented from passing beneath the coating and initiating corrosion.

The functions of Cashew Oil at the molecular and polymeric level may differ depending on the application:

Imparting internal flexibility (internal plasticization) to rigid epoxy structures

Providing matrix binding and heat dissipation in friction materials

Creating excellent adhesion on damp and wet surfaces (wet adhesion)

Increasing the water and salt spray resistance of the coating

Reducing internal stresses and micro-cracks during curing

Providing fast curing by maintaining reactivity even at low temperatures

Supporting cathodic protection against severe corrosion conditions

Acting as a viscosity-reducing reactive diluent in epoxy-amine reactions

Increasing impact resistance in phenolic casting resins

Supporting vulcanization and adhesion in rubber compounds

The presence of the phenolic ring in the structure of CNSL enables a Mannich reaction with amine groups, leading to the formation of epoxy hardeners called "Phenalkamines". Phenalkamines are capable of curing epoxy quickly even on icy and damp surfaces.

The rate of the curing reaction is directly related to the structure of the amine used, temperature, the reactor environment and the presence of a catalyst. Many CNSL-modified resins are offered in phenalkamine form in order to reduce drying time. Therefore, CNSL should not be evaluated on its own, but together with the target resin system.

The resulting hydrophobic network structure and phenolic bonds are exceptionally stable against humid and saline environments. For this reason, CNSL-epoxy systems are preferred in structures exposed to seawater and heavy industrial atmospheres.

However, it should not be assumed that Cashew Oil will deliver the same flexibility and performance in every resin system. The equivalent weight and viscosity of the epoxy used, the CNSL ratio and the curing conditions should be evaluated through laboratory trials.

WHICH INDUSTRIES USE CASHEW OIL?

Thanks to its highly hydrophobic structure, its aliphatic chain providing internal flexibility, and its reactive phenolic structure, Cashew Oil is a functional bio-based raw material used in various industrial fields, primarily heavy-duty coatings. The purpose of use may vary depending on the product's grade, purity and the formulation system.

Main areas of use:

Marine and ship paints (Marine coatings)

Heavy corrosion protection and industrial coatings

Brake linings and friction materials (Friction dust)

Surface-tolerant anti-corrosion primers (Surface tolerant primers)

Concrete and floor coating epoxies

Electrical insulating varnishes and casting resins

Automotive underbody and chassis protectants

Rubber and tire industry (Reactive softener/tackifier)

Foundry sand binder resins

Wood preservatives and phenolic adhesives

Laminate and composite production

Bio-based epoxy hardener (Phenalkamine) manufacturing

The most common use of Cashew Oil is in marine structure coatings and anti-corrosion primers prepared with epoxy resins. These systems are preferred especially on steel surfaces exposed to seawater, high humidity and aggressive chemical environments.
The performance each industry expects from Cashew Oil is different. For example, a ship paint manufacturer focuses on adhesion to damp surfaces and salt water resistance, a brake lining manufacturer on thermal stability and heat dissipation at high temperatures, while a floor coating manufacturer may prioritize flexibility and impact absorption.

USE OF CASHEW OIL IN PAINT, COATING AND EPOXY SYSTEMS

In paint and coating formulations, Cashew Oil is used in epoxy systems either directly as a reactive diluent/modifier or through its derivative phenalkamine hardeners. This combination is commonly referred to in the industry as "CNSL Modified Epoxy" or "Phenalkamine Cured Epoxy Coating".

Possible functions of Cashew Oil in coatings are:

Forming flexible bonds with epoxy resin

Increasing waterproofing and salt water resistance

Improving wetting on damp and rusty surfaces

Supporting low-temperature curing

Increasing film flexibility and impact resistance

Reducing volumetric shrinkage during curing

Reducing the tendency to crack and peel

Contributing to salt spray corrosion resistance

CNSL-modified coatings can be evaluated especially in applications such as ship hulls, ballast tanks, pipelines, steel bridges, offshore platforms and industrial concrete floors.
In epoxy systems, Cashew Oil can typically be added as a reactive modifier at 5% to 20% of the binder portion. In phenalkamine hardener production, it is used as the main reactant. The correct ratio is determined stoichiometrically according to the equivalent weight of the epoxy and the targeted degree of flexibility.
CNSL-based phenalkamine epoxy systems can generally dry within a few hours even at temperatures as low as 0 °C and in high-humidity environments. Exact curing conditions should be determined according to the technical data of the selected hardener and epoxy resin.
When selecting Cashew Oil in coating production, viscosity, color index, moisture content, cardanol percentage and compatibility with the epoxy resin should be evaluated.
Whether a CNSL product will give the same flexibility result with every epoxy resin cannot be inferred from the name "Cashew Oil" alone. The usage ratios and curing conditions recommended by the resin and hardener manufacturer should be taken as the basis.

FRICTION MATERIAL, AUTOMOTIVE AND ELECTRICAL APPLICATIONS OF CASHEW OIL

In a suitable quality grade and in dust form (Friction Dust), Cashew Oil can be evaluated as a binder and thermal stabilizer in brake linings, clutch discs, electrical insulation materials and special casting resins.

Functions for which Cashew Oil can be evaluated in these applications include:

Providing heat dissipation at high temperatures in friction materials

Reducing lining wear and providing quiet braking

Increasing impact strength in the thermoset system

Contributing to electrical insulation properties

Supporting crack resistance against thermal shock

Imparting heat resistance by forming cross-links with other phenolic resins

When purchasing Cashew Oil for friction and electrical applications, the following points should be checked:

Ash and metallic impurity content

Viscosity and degree of polymerization

Moisture and volatile matter content

Free phenol level

Color and homogeneity

Current technical specification

Certificate of analysis (COA)

Safety data sheet (SDS)

Manufacturer and batch traceability

Low moisture and stable viscosity are important, particularly in brake lining manufacturing, to prevent gas bubble formation during hot pressing and to ensure homogeneous braking performance.
Likewise, a liquid CNSL product suitable for coatings cannot automatically be said to be suitable for brake lining dust manufacturing or electronic applications. The relevant quality requirements and manufacturer documents should be checked for each application.

IS CASHEW OIL USED IN COSMETIC, FOOD AND PHARMACEUTICAL APPLICATIONS?

Cashew Oil (CNSL) is not a substance used as a raw material in cosmetics, personal care, food, pharmaceutical or biotechnology products. The product's field of use is limited to industrial coatings, friction materials and polymer systems.
The phenolic compounds in raw CNSL (especially cardol and anacardic acid) can exhibit vesicant properties (causing skin irritation and blistering). This safety classification makes the product unsuitable for use in products that come into direct contact with the human body or are consumed. Therefore, there is no INCI name, food additive number or pharmacopoeia definition for Cashew Oil.
Within a cured epoxy or phenolic film, CNSL is present in a state chemically bonded to the polymer network. However, if coated products are intended for use on food-contact surfaces, the compliance of the final coating with the relevant food contact legislation should be assessed separately.
Companies looking for raw materials for cosmetic, food or pharmaceutical purposes need to evaluate alternative vegetable oils or ingredients specifically defined for these applications and compliant with the relevant legislation.

INDUSTRIAL APPLICATIONS OF CASHEW OIL

Due to its high hydrophobicity, aliphatic chain flexibility and phenolic reactivity, Cashew Oil is an important bio-based raw material used in numerous industrial polymer and coating systems.

The following functions may stand out in industrial CNSL applications:

Reactive flexibilization (Internal plasticization)

Phenalkamine hardener production

Corrosion prevention and water repellency

Damp surface wetting

Friction and wear control

Heat dissipation and thermal stability

Viscosity reduction (Reactive diluent)

Increased impact resistance

Tackifier function

Cathodic disbondment resistance

Support for adhesion to concrete and steel

In marine structures, CNSL derivatives help protect steel surfaces against corrosion and seawater for many years. For this reason, they are frequently preferred in ballast tank and hull paints.
In general industrial primers, Cashew Oil penetrates rusty surfaces and supports adhesion in cases where surface cleaning cannot be done perfectly (limited blasting possibilities).
In the rubber and foundry sectors, CNSL can be evaluated to increase the processability of the elastomer matrix and to raise impact strength after curing.

The following issues should be evaluated when using Cashew Oil in industrial systems:

Viscosity and flowability

Cardanol / Cardol ratio

Degree of thermal decarboxylation

Epoxy or formaldehyde reactivity

CNSL usage ratio (5% - 20%)

Amine or catalyst type

Ambient temperature and humidity level

Curing time

Color sensitivity (Tendency to darken)

Volatile matter and moisture content

Corrosion performance requirements of the final coating

WHAT PROBLEMS CAN CASHEW OIL HELP SOLVE?

Cashew Oil can help solve various problems in coating and polymer systems related to embrittlement, corrosion, moisture-related loss of adhesion, high viscosity and slow curing. However, its effect depends on the resin used, the CNSL ratio and ambient conditions.

Slow curing and failure to dry in cold and humid weather

Synthetic epoxy hardeners can become unstable or cause amine blush at low temperatures (0-10 °C) and high humidity. CNSL-derived phenalkamines can help achieve fast drying by continuing the reaction even in the presence of water.
However, the use of CNSL alone does not guarantee instant drying under all conditions. Ambient temperature, epoxy type and hardener stoichiometry should be evaluated together.

Embrittlement and cracking of the coating over time

Externally added plasticizers (phthalates, etc.) migrate out of the film over time and lead to embrittlement. Because CNSL bonds reactively to the molecule, it provides permanent flexibility and helps prevent cracking.

Loss of adhesion on rusty surfaces with poor surface preparation (where blasting is not possible)

The low surface tension and phenolic structure of Cashew Oil allow it to wet micro-rough and damp surfaces excellently. This can help improve the adhesion of surface-tolerant primers.

Corrosion progression under salt spray

The hydrophobic barrier formed by the long aliphatic side chains prevents water and salt ions from reaching the metal surface. It contributes to preventing underfilm corrosion creep.

Need for solvent due to excessively high viscosity

CNSL and distilled cardanol help achieve workability by reducing viscosity in epoxy resins without increasing the VOC (volatile organic compound) level.

High-temperature fading (loss of grip) and noise in brake linings

CNSL-based friction dusts can contribute to reducing brake noise and lining wear by distributing heat homogeneously at high temperatures.

POINTS TO CONSIDER WHEN USING CASHEW OIL

One of the most common mistakes in using Cashew Oil is assuming that all CNSL products have the same viscosity and color and can be used at the same ratio in every epoxy system. In fact, cardanol content, viscosity and moisture level are decisive in determining the correct formulation.

The following points should be taken into account when using Cashew Oil:

A refined CNSL or Cardanol form suited to the intended use should be selected.

Viscosity and phenolic OH value should be checked.

In systems where color stability is expected, distilled cardanol should be preferred over raw CNSL.

The equivalent weight (EEW) of the epoxy resin should be taken into account.

Stoichiometric ratios and addition percentages should be calculated correctly.

Moisture and volatile matter content should be checked.

The tendency of the paint to yellow and darken should be taken into account.

Curing speed and gel time should be verified.

Contact with air during storage should be minimized (risk of autoxidation).

Dosage and formulation should be determined through laboratory trials.

Compatibility with other solvents and additives should be tested.

Manufacturer TDS and SDS documents should be reviewed.

Batch-based analysis results should be verified via the COA.

Cashew Oil (especially raw and decarboxylated forms) is a substance that can cause skin sensitization or irritation because it contains phenolic compounds. During weighing, reactor charging and mixing, closed systems, local exhaust ventilation, adequate ventilation and personal protective equipment (nitrile gloves, goggles) should be used to prevent skin contact and inhalation of vapors. Safe working procedures should be determined according to the product's current SDS.
In paint manufacturing plants, controlling exposure to heat and air in storage tanks and transfer lines is also important.

STARTING FORMULATION APPROACHES FOR CASHEW OIL

The following examples are starting approaches prepared to show how Cashew Oil can be evaluated in the formulation development process. They are not validated commercial recipes, production instructions or regulation-compliant final formulas.
The ratios given are example starting levels for preliminary laboratory trials. The type of epoxy resin used, CNSL purity and hardener content can significantly change performance. Laboratory trials, corrosion tests, occupational safety checks and checks against the relevant legislation should be carried out for each application.

EXAMPLE 1: PRELIMINARY TRIAL OF A SURFACE-TOLERANT ANTI-CORROSION EPOXY PRIMER

Objective: To develop a bio-based epoxy primer providing excellent adhesion and salt water resistance on damp and rusty steel surfaces.

Starting approach:

Bisphenol A Epoxy Resin (EEW ~190): 35–40%

Cashew Oil / Distilled Cardanol (Reactive Modifier): 5–10%

Thiol / Amine derivative or Phenalkamine Hardener: 15–20%

Zinc Phosphate (Anti-corrosive pigment): 10–15%

Barium Sulfate / Talc (Filler): 15–20%

Xylene / Butanol (Solvent blend): 8–12%

Wetting and Anti-settling Additive: 0.5–1.0%

Impact resistance and hydrophobicity are increased by keeping the CNSL modifier ratio at around 10% of the binder portion.

Application approach:

Resin, solvent and CNSL modifier are mixed.
Pigments and fillers are added and dispersed in a high-speed mixer (dissolver).
The prepared Component A is mixed with Component B (hardener) at the recommended ratio.
The mixture is applied to lightly rusted and damp test panels.
Drying times are observed at room temperature or in a cold environment.
Flexibility (mandrel flexibility), adhesion (cross-cut) and Salt Spray corrosion tests are performed on the cured panels.
Equipment that prevents skin contact should be used when transferring CNSL-containing raw materials.

EXAMPLE 2: MANNICH REACTION APPROACH FOR PHENALKAMINE HARDENER PRODUCTION

Objective: To obtain an epoxy hardener intermediate providing low-temperature curing.

Starting components:

Decarboxylated CNSL / Cardanol: 45–50%

Aliphatic Polyamine (e.g. EDA or DETA): 25–30%

Formaldehyde solution: 15–20%

Catalyst / Solvent: According to the formulation

CNSL and polyamine are charged to the reactor and formaldehyde is added dropwise at a controlled temperature (Mannich condensation).

Application approach:

Water is removed while keeping the temperature under control.
At the end of the reaction, water and unreacted monomers are removed under vacuum.
The viscosity and Amine Value of the resulting phenalkamine hardener are measured.
Gel time with epoxy resin is measured at different curing temperatures (0 °C, 10 °C, 23 °C).
An adhesion test is applied underwater or on damp concrete.
The phenalkamine structure providing the most balanced drying is determined.
It should not be assumed that a single reaction ratio will give the same reactivity across all coating classes.

EXAMPLE 3: PREPARATION OF BRAKE LINING FRICTION DUST

Objective: To obtain a CNSL-based thermoset friction dust for use in automotive brake linings.

Starting approach:

Technical / Decarboxylated CNSL: 70–75%

Hexamethylenetetramine (Hexa / Curing agent): 8–12%

Acid catalyst / Filler: 10–15%

Polymerization and cross-linking are completed by gradually raising the temperature.

Application approach:

CNSL is heated in the reactor and the catalyst/Hexa is added.
The reaction is continued until the mass hardens, passing into a rubbery and then a brittle thermoset structure.
The resulting gel/polymer is cooled and broken up.
It is ground in a mill to the desired micronized particle size (e.g. 100-200 mesh).
The prepared dust is added to the brake lining formulation and hot pressing tests are carried out.
Friction coefficient, wear rate and high-temperature fading behavior are measured.
In such evaluations, the cross-link density of the product, not just the reactor temperature, should be taken as the basis.

PRODUCTS SIMILAR TO CASHEW OIL AND ALTERNATIVES

An alternative to Cashew Oil is not simply a matter of choosing another bio-based oil. When determining an alternative, the targeted hydrophobicity, phenolic reactivity, viscosity, color stability, mechanical flexibility, occupational safety requirements and final product corrosion performance should be evaluated together.

CASHEW OIL AND DISTILLED CARDANOL

Distilled Cardanol is the form of Cashew Oil (CNSL) purified by vacuum distillation. Therefore, a comparison between the two evaluates the raw/technical source versus the refined main component.
Compared with Raw CNSL, Distilled Cardanol has a much lighter color, lower viscosity and higher chemical purity. This property makes it possible to reduce color darkening in paints and to obtain lower-viscosity resin systems.
The expression CNSL denotes the general raw material source, while Cardanol defines a specific refined component. Therefore, viscosity and color parameters should be tested when switching between the two products.

CASHEW OIL AND HYDROLYZED/SYNTHETIC PHENOLS (BISPHENOL A, NONYLPHENOL)

Nonylphenol and Bisphenol A are synthetic phenolic compounds used in the manufacture of epoxy hardeners and resins.
CNSL and Cardanol are a natural and renewable source compared with synthetic phenols. In addition, thanks to its long aliphatic chain, it offers much higher internal flexibility and corrosion resistance than Nonylphenol.
Nonylphenol is subject to environmental and toxicological restrictions (REACH restrictions) in some regions. CNSL-based Cardanol is widely substituted for Nonylphenol as a bio-based and safe alternative.
Therefore, when a switch from Nonylphenol to Cardanol is planned, it is recommended to make adjustments to reactivity and viscosity.

CASHEW OIL AND OTHER VEGETABLE OILS (SOYBEAN, LINSEED, CASTOR OIL)

Traditional vegetable oils such as soybean, linseed or castor oil are also used as modifiers in polymers.
However, these oils do not contain a phenolic ring; they generally have an ester or triglyceride structure. Therefore, they cannot undergo a direct phenalkamine reaction with epoxy and cannot offer high chemical/corrosion resistance.
CNSL offers hardness, adhesion and chemical resistance thanks to the phenolic ring in its structure, while combining in a single molecule the flexibility that vegetable oils provide through its aliphatic chain.
Therefore, standard vegetable oils cannot be a direct substitute for Cashew Oil in anti-corrosion epoxies.

CASHEW OIL AND REACTIVE SYNTHETIC DILUENTS (C12-C14 GLYCIDYL ETHER)

Aliphatic glycidyl ethers are frequently used as viscosity reducers in epoxy systems.
These diluents reduce viscosity very effectively but can weaken the water resistance and corrosion protection of the coating.
Cashew Oil / Cardanol-based reactive modifiers, on the other hand, reduce viscosity while also increasing hydrophobicity and supporting corrosion resistance.
In selecting an alternative, the targeted corrosion performance, mechanical strength, color expectation and cost should be determined through comparative laboratory tests.

QUALITY CONTROL AND PURCHASING CRITERIA FOR CASHEW OIL

When purchasing Cashew Oil, deciding based solely on product name and price is not sufficient. In particular, different forms such as Raw CNSL, Decarboxylated CNSL and Distilled Cardanol, as well as products from different manufacturers, may have different technical properties.

Information recommended for review before purchase:

Product name and manufacturer

CNSL form (Raw, Decarboxylated or Distilled Cardanol)

CAS number

EC / EINECS number

Viscosity value (cPs or mPa.s at 25 °C)

Phenolic Hydroxyl Value / Reactivity ratio

Cardanol and Cardol percentage

Moisture content (%)

Ash content (%)

Volatile matter content

Color value (Gardner or APHA scale)

Technical data sheet (TDS)

Safety data sheet (SDS)

Certificate of analysis (COA)

Production and batch information

Packaging type (Drum, IBC, bulk) and net quantity

Storage conditions and heat sensitivity

Shelf life or retest information

REACH and bio-based content compliance information

The COA shows the analysis results of a specific batch of Cashew Oil. The TDS describes the general technical properties of the product and its recommended areas of use. The SDS contains information on safe use, transport, storage and emergencies.
These documents are not substitutes for one another; they should be evaluated together.
In particular, when purchasing Cashew Oil, the manufacturer should be asked whether the product is Raw CNSL, Decarboxylated or Distilled Cardanol, along with its viscosity and moisture content. This is because products with different reactivity and color may be found under the same Cashew Oil name.

STORAGE AND TRANSPORT OF CASHEW OIL

Cashew Oil should be stored under the conditions recommended by the manufacturer, in a cool, dry and well-ventilated area, in its tightly closed original packaging.
The product should not be exposed to high temperatures, direct sunlight, moisture or heat sources. Prolonged contact with air (oxygen) can cause autoxidation of the unsaturated aliphatic chains and an increase in viscosity (thickening).
CNSL should be stored separately from strong oxidizing agents, strong acids, concentrated bases and isocyanates.
After the packaging is opened, it is important to protect the product from moisture and contamination. Nitrogen blanketing inside the packaging for partially used stocks helps preserve color and viscosity stability.
Leaks should be kept under control during transfer and pumping operations, and in case of spillage, the cleaning procedures with absorbent materials specified in the SDS should be followed.
Products that have been stored for a long time or have shown an excessive increase in viscosity should be re-analyzed in line with the manufacturer's specifications.

CASHEW OIL SAFETY INFORMATION

The safe use of Cashew Oil depends on the current SDS of the supplied product and the implementation of appropriate occupational safety measures.
Cashew Oil (especially raw forms) is a substance that, due to the phenolic components it contains (cardol, etc.), can cause irritation, redness and sensitization (dermatitis) on contact with the skin. Current hazard and precautionary statements should be checked in the supplier's SDS.
CNSL and Cardanol components exhibit a more readily biodegradable character in nature compared with substances such as synthetic Nonylphenol that cause lasting environmental harm. Nevertheless, spillage of chemical substances into water sources and soil should be prevented. The current regulatory status should be followed through the relevant official sources.
Skin contact with liquid Cashew Oil in particular, and inhalation of vapors formed in hot processes, should be prevented. During weighing, reactor charging, mixing and paint application, closed systems, local exhaust ventilation, adequate ventilation, respiratory protection, protective nitrile/butyl gloves, eye protection and work clothing should be used.
Personal protective equipment should be used in full during tank cleaning and spill response in facilities.
Within a cured epoxy or phenolic coating film, Cashew Oil is present in a state bonded to the polymer network. Safety precautions are particularly important in the pre-curing stages, namely raw material handling, resin manufacturing and paint application processes.
It should not be assumed that safety information is the same for products from different manufacturers or of different refinement grades (Raw vs. Distilled). The current SDS and the manufacturer's technical documentation should be taken as the basis.

WHAT SHOULD BE CONSIDERED WHEN PURCHASING CASHEW OIL?

The first step in sourcing Cashew Oil is to clarify for what purpose and with which resin system the product will be used. The quality criteria sought for a marine anti-corrosion primer, floor epoxy, brake lining dust, electrical varnish or phenalkamine production may not be the same.
Therefore, rather than writing only "Cashew Oil" or "CNSL" in a purchase request, specifying the field of use, the resin system and the targeted technical performance allows a more accurate product evaluation.

The following information should be clarified before purchase:

Industry of use and final application

Required CNSL form (Raw, Decarboxylated, Distilled Cardanol)

Expected viscosity and flowability range

Required color class (Gardner grade)

Upper limits for moisture and ash content

Type of epoxy or phenolic resin to be used

Required physical packaging (Drum, IBC, bulk tank)

Required quality standard and degree of purity

Requirement for manufacturer and origin information

TDS, SDS and COA requirements

Bio-based content and REACH compliance documents

If substituting an existing product, the technical properties of the existing product (Viscosity, OH value, etc.)

The price of Cashew Oil may vary depending on the product form (raw vs. distilled cardanol), purity, viscosity, color grade, manufacturer, order quantity, packaging type, origin, logistics and current global market conditions. Therefore, the current Cashew Oil price should be evaluated through a quotation together with the product specification and delivery terms.

CASHEW OIL SUPPLY FROM ATAMAN KIMYA

Cashew Oil (Cashew Nut Shell Liquid) is an important bio-based chemical raw material evaluated for different technical functions in epoxy and phenolic systems, such as reactive flexibilization, corrosion prevention, providing water resistance, adhesion to damp surfaces and viscosity reduction. It is important for manufacturers planning to purchase the product to clarify, before ordering, the Cashew Oil form suitable for their field of use, its technical properties, quality grade and the required documents.
Companies wishing to obtain information about Cashew Oil supply from Ataman Kimya can request information on product suitability, current supply status, packaging options and price quotations by sharing their fields of use and technical requirements.
The product's current stock status, origin, CNSL form (Raw, Decarboxylated or Distilled Cardanol), technical properties, packaging and specifications should be confirmed with Ataman Kimya before ordering.

Sharing the following information in a quotation request makes it easier to evaluate the right Cashew Oil product:

Industry of use and final application

Requested CNSL form or Cardanol grade

Targeted viscosity and color expectation

Information on the epoxy/phenolic resin used

Requested quality standard

Estimated order quantity

Required packaging type (Drum, IBC, etc.)

Requested technical documents

TDS or COA information of the existing product, if any

FREQUENTLY ASKED QUESTIONS ABOUT CASHEW OIL

What is Cashew Oil (CNSL)?
Cashew Oil (Cashew Nut Shell Liquid) is a natural, bio-based chemical raw material obtained from the shell of the cashew nut, containing a phenolic ring and a 15-carbon unsaturated aliphatic side chain.

What does CNSL stand for?
CNSL is the English abbreviation of Cashew Nut Shell Liquid. It is also known as Cashew Oil or Cashew Nut Shell Oil.

What is the CAS number of Cashew Oil?
The general CAS number for raw and technical CNSL is 8007-24-7. CAS 37330-39-5 is used for the purified Cardanol component.

What is the EC / EINECS number of Cashew Oil?
The EC / EINECS number for Cashew Oil (CNSL) is listed as 232-355-4.

What is the basic chemical structure of Cashew Oil?
The representative molecular formula of Cardanol, the main component of Cashew Oil, is C₂₁H₃₂O, with a molecular weight of approximately 300.5 g/mol.

Does Cashew Oil have an INCI name?
No. Cashew Oil is an industrial raw material and, since it is not used as a cosmetic product, it has no defined INCI name.

What is Cashew Oil used for?
Cashew Oil is used as an internal flexibilizer in epoxy systems, an anti-corrosion modifier, a raw material for phenalkamine hardeners, a friction agent in brake linings and a damp-surface adhesion promoter.

Which industries use Cashew Oil?
Cashew Oil is used in marine paints, heavy industrial coatings, automotive brake linings, floor epoxies, casting resins, electrical varnishes and rubber manufacturing.

How does Cashew Oil work in epoxies?
While the phenolic group of Cashew Oil reacts with epoxy or amine structures, the 15-carbon aliphatic chain creates flexibility and high water repellency (hydrophobicity) in the polymer matrix.

What is the usage ratio of Cashew Oil in epoxy systems?
The typical usage ratio is between 5% and 20% of the binder portion, depending on the resin system. The exact ratio should be determined by stoichiometric calculations and performance tests.

What is a phenalkamine hardener?
A phenalkamine is an epoxy hardener produced by the Mannich reaction of Cashew Oil (CNSL), formaldehyde and polyamines, providing fast curing at low temperatures and in humid environments.

What is the difference between Cashew Oil and Distilled Cardanol?
Cashew Oil refers to the natural raw or decarboxylated source, while Distilled Cardanol is the lighter-colored, lower-viscosity form of this source purified by distillation.

How does Cashew Oil increase corrosion resistance?
Thanks to its long aliphatic chains, the hydrophobic barrier it forms prevents water and salt ions from reaching the metal surface and reduces cathodic disbondment.

Why is Cashew Oil preferred in surface-tolerant paints?
Thanks to its low surface tension and phenolic structure, it wets micro-rusted and damp surfaces very well, providing high adhesion.

Can Cashew Oil be used instead of Nonylphenol?
Yes. Due to its bio-based structure, harmless profile and the high flexibility/water resistance it offers, it is the most effective natural alternative to Nonylphenol in epoxy systems.

Is Cashew Oil used in cosmetics or food?
No. Due to its phenolic structure, it can irritate the skin. It is used only in industrial polymer and coating applications.

Is Cashew Oil a hazardous substance?
In liquid/raw form, CNSL can cause allergic reactions or irritation on skin contact due to its phenolic structure. Appropriate personal protective equipment should be used and the SDS should be taken as the basis.

Is Cashew Oil a bio-based product?
Yes. It is a renewable and sustainable bio-based raw material obtained from 100% natural cashew nut shells.

Is a coating containing cured Cashew Oil safe?
Yes. Once curing is complete, CNSL is chemically bonded to the polymer network. The risks lie mainly in the handling stage of the liquid raw material.

Is Cashew Oil soluble in water?
No. It is insoluble in water and highly hydrophobic. It dissolves readily in organic solvents and resins.

What does Cashew Oil look like?
It is a viscous liquid, dark brown or reddish-brown in color, or dark amber in refined forms.

What is the viscosity of Cashew Oil?
Depending on the grade, it can vary between 150 cPs and 600 cPs at 25 °C. It is lower in distilled cardanol forms.

What does the price of Cashew Oil depend on?
The price may vary depending on the product's degree of refinement (raw vs. distilled cardanol), viscosity, color, purity, packaging, order quantity and global raw material markets.

What are the alternatives to Cashew Oil?
Nonylphenol, synthetic reactive diluents, soybean/linseed-based dimer acids and synthetic phenolic modifiers can be alternatives, but none of them can fully deliver the corrosion and moisture performance of CNSL.

How should Cashew Oil be stored?
It should be stored in a cool, dry, ventilated environment, in its tightly closed original packaging, away from heat and sunlight. Nitrogen blanketing is recommended.

Which documents should be requested when purchasing Cashew Oil?
TDS, SDS and COA are the basic documents. Bio-based compliance and REACH documents may also be requested.

Which technical properties are important when purchasing Cashew Oil?
Viscosity, phenolic hydroxyl value, moisture content, color grade, cardanol percentage and ash content are the most critical parameters.

What is the molecular weight of Cashew Oil?
Based on the main Cardanol component, the molecular weight is approximately 300.5 g/mol.

CASHEW OIL – TECHNICAL SUMMARY

Cashew Oil, Cashew Nut Shell Oil or Cashew Nut Shell Liquid, CNSL for short, is a bio-based phenolic compound obtained from cashew shells, carrying a 15-carbon unsaturated aliphatic chain attached to a phenolic ring, with a representative molecular formula of C₂₁H₃₂O and a molecular weight of approximately 300.5 g/mol. It may be searched for under different names such as Cashew Nut Shell Liquid, Cardanol, Decarboxylated CNSL and Phenalkamine Precursor.
Cashew Oil is not a single commercial product type. Although forms such as Raw CNSL, Decarboxylated CNSL and Distilled Cardanol come from the same natural source, their viscosity, color stability, cardanol percentage and processing behavior may differ. Phenolic hydroxyl value, moisture content and purity are also important parameters affecting performance.
CAS No 8007-24-7 and EC No 232-355-4 are used for the general CNSL registration. Since a separate registration such as CAS 37330-39-5 exists for Distilled Cardanol, the exact chemical identity and form of the product should be checked at the time of purchase.
Cashew Oil is mainly used in epoxy coatings as a reactive flexibilizer, an anti-corrosion modifier and a raw material for phenalkamine hardeners. It helps provide water resistance, damp-surface adhesion, impact absorption, low-temperature curing, surface tolerance and chemical resistance. Performance depends on the type of epoxy resin, the CNSL ratio, curing conditions and the hardener structure.
Since CNSL can irritate the skin during handling due to its phenolic structure, appropriate occupational safety measures should be taken during its use and the current SDS should be taken as the basis. Selecting the correct form of Cashew Oil, which can be evaluated in marine coatings, heavy industrial primers, floor epoxies, brake linings and rubber applications, is important for final product performance.
Companies planning to source Cashew Oil from Ataman Kimya are advised to confirm current product, stock, origin, packaging and quotation information by sharing their field of use, requested CNSL form (Raw vs. Distilled Cardanol), viscosity expectation, epoxy resin used, quality standard, quantity and technical documentation requirements.