Pale Pressed Grade Castor Oil (PPG): Technical Properties and Industrial Performance

1. Technical Overview

Pale Pressed Grade (PPG) Castor Oil is a premium, high-purity triglyceride produced by the initial pressing of top-quality castor seeds.² Unlike standard commercial or industrial grades, PPG is distinguished by its extremely light color and significantly lower acidity and impurity levels.³ Chemically, it is defined by a high concentration of Ricinoleic acid (approx. 90%), which provides a unique secondary hydroxyl group. In high-precision industrial applications, PPG is the preferred choice where color stability and chemical neutrality are critical to the final formulation’s integrity.

2. Chemical Structure & Composition

The molecular architecture of PPG is characterized by a high degree of uniformity. As it is derived from the first pressing, it contains the highest concentration of pure triglycerides.

• Ricinoleic Acid (~90%): The primary source of functionality.⁴

• Low Free Fatty Acids (FFA): Minimal chain degradation ensures a stable pH.

• Phospholipid Profile: Negligible levels of gums and phosphatides compared to solvent-extracted grades.

The absence of oxidation products in the first-press stage ensures that the double bonds in the carbon chain remain intact, providing predictable reactivity for downstream synthesis.

3. Physical & Chemical Properties

PPG is a clear, viscous liquid with the following technical benchmarks:

• Color: Significantly lighter than FSG (First Special Grade), usually characterized as a pale straw color.⁵

• Viscosity: ~7.0 to 9.0 stokes at 25°C.

• Hydroxyl Value: 160 min, indicating high reactivity for polyurethane and esterification reactions.

• Moisture Content: Strictly controlled below 0.20% to prevent hydrolysis.

• Refractive Index: 1.477 to 1.481 at 25°C.⁶

4. Reaction Chemistry

Due to its superior purity, PPG reacts more predictably in a reactor:

1. Urethane Synthesis: The hydroxyl groups react with isocyanates to form high-clarity elastomers.

2. Esterification: Reacts with organic acids to produce high-purity esters with minimal byproduct formation.

3. Ethoxylation: Its clean profile allows for the production of light-colored non-ionic surfactants used in the pharmaceutical and cosmetic industries.

5. When to Use vs. When NOT to Use

Use PPG when:

• Formulating “Water-White” or clear coatings where the slightest yellow tint is a failure.

• Manufacturing pharmaceutical intermediates or topical ointments.

• Producing high-performance lubricants for food-grade machinery or sensitive instrumentation.

Do NOT use PPG when:

• The application is a standard industrial lubricant where color and low acid value are not critical (Commercial Grade is more cost-effective).

• The oil will be subjected to crude industrial processes like sulfonation for textile use, where the extra purity of PPG provides no functional benefit.

6. Compatibility Profile

PPG exhibits excellent synergy with:

• Natural Polymers: Shellac, rosin, and vegetable waxes.

• Synthetic Resins: Polyurethanes, epoxies, and polyamides.

• Solvents: Fully soluble in isopropyl alcohol, ethyl acetate, and aromatic hydrocarbons.

7. Manufacturing Process (Product Focus)

The production of PPG at Nova Industries is a mechanical extraction process:

1. Seed Selection: Only the brightest, most mature seeds from North Gujarat are selected.

2. Pale Pressing: Seeds are subjected to the first round of mechanical pressing without the use of chemical solvents.⁷

3. Refining: The oil undergoes a specialized bleaching process using activated earth to remove any trace organic pigments.⁸

4. De-moisturization: High-vacuum drying ensures that moisture levels are kept at a minimum to preserve the shelf life and performance.

8. Technical Specifications Table

Parameter	Specification (Pale Pressed Grade)
Appearance	Pale Yellow, Clear & Bright
Acid Value (mg KOH/g)	1.0 Max
Iodine Value (Wijs)	82 – 90
Saponification Value	176 – 187
Hydroxyl Value	160 – 168
Moisture & Volatiles	0.20% Max
Color (Lovibond 5.25″ Cell)	Yellow 15 / Red 1.5 Max
Relative Density (at 30°C)9	0.954 – 0.96010

9. Quality Grade Analysis

The primary differentiator for PPG is the Acid Value. While First Special Grade (FSG) allows for an Acid Value of up to 2.0, Nova Industries’ PPG is capped at 1.0. This lower acidity significantly reduces the risk of corrosion in metallic systems and prevents the premature gelation of sensitive resins.

10. Impact of Impurities

• Trace Metals: Higher grades like PPG must have minimal iron and copper content to prevent the darkening of finished products.

• Peroxide Value: Low peroxide values in PPG indicate that the oil has not begun the oxidation process, ensuring better storage stability for the customer.¹¹

11. Industry-Wise Application 1: Pharmaceuticals

PPG is used as a vehicle for drug delivery and as a starting material for various therapeutic derivatives. Its high purity ensures it does not interact negatively with active pharmaceutical ingredients (APIs).

12. Industry-Wise Application 2: Cosmetics & Personal Care

In high-end lipsticks, shampoos, and hair oils, PPG provides superior emolliency and shine.¹² Its light color ensures it does not affect the shade of the added pigments or dyes.

13. Industry-Wise Application 3: High-Performance Lubricants

Used in specialized greases where low-temperature fluidity and high-temperature stability are required. It is often used in lubricants for the food processing and aerospace industries.

14. Industry-Wise Application 4: Specialty Chemicals

A preferred feedstock for producing high-purity Sebacic acid and Undecylenic acid, used in the production of high-grade Nylon 6,10 and Nylon 11.

15. Formulation Guide

• Incorporation: Add PPG slowly under moderate agitation to ensure uniform blending with resins.

• Heating: If the application requires pre-heating, do not exceed 60°C for extended periods to maintain the pale color.

16. Sustainability Data

Pale Pressed Castor Oil is a 100% natural, renewable, and biodegradable material. It provides a non-toxic, eco-friendly alternative to synthetic polyols and mineral-based oils.

17. Packaging & Logistics (Technical)

• Drums: 200kg HDPE or Epoxy-lined MS Drums to maintain color purity.

• IBCs: 1-ton Intermediate Bulk Containers for industrial use.¹³

• Protection: Always store under nitrogen blanketing if possible once the original seal is broken to prevent oxidation.

18. Storage Science

PPG should be stored in a cool, dry place. Because of its light color, it is particularly sensitive to UV light, which can cause slight yellowing over time. Stainless steel tanks (Grade 304 or 316) are recommended for bulk storage to prevent trace metal contamination.

19. Troubleshooting Guide

• Problem: Slight yellowing in the final product. Solution: Ensure the PPG was not exposed to high heat or direct sunlight before use.

• Problem: Sedimentation at low temperatures. Solution: This is natural for vegetable oils; gently warm the oil to 30°C to return it to a clear state.

20. Regulatory Compliance

Our PPG Castor Oil is REACH Compliant and produced in accordance with GMP-aware standards, making it suitable for use in regulated global markets.

21. Safety (SDS Summary)

• Handling: Standard PPE (gloves and goggles) is recommended.

• Fire: Use dry chemical, CO2, or foam extinguishers.

• Environment: PPG is biodegradable and non-toxic to aquatic systems.¹⁴

22. Sample Validation Process

For laboratory trials, we recommend performing a Lovibond Color Test and Acid Value check. For cosmetic or pharmaceutical applications, a clarity check at 10°C is also advised.

23. Commercial Efficiency

By using PPG, manufacturers reduce the need for expensive bleaching or neutralizing steps in their own production lines. The consistency of the first-press oil ensures that production parameters remain stable, reducing waste and downtime.

24. Technical FAQs

1. Is PPG the same as Cold Pressed Oil? While similar, PPG refers to the quality and refinement level (first pressing), whereas “Cold Pressed” specifically denotes the temperature control during extraction. PPG is refined to ensure industrial consistency.

2. Can PPG be used for polyurethane coatings? Yes, its low acidity and high hydroxyl value make it an excellent choice for high-clarity PU resins.

3. What is the shelf life of PPG? When stored correctly in a sealed container, PPG maintains its specifications for 12 to 24 months.

25. Contact CTA

For Technical Data Sheets (TDS), specific Lovibond color requirements, or to request a sample of our Pale Pressed Grade, please contact our export division at: export@novaind.in