Cyclohexasiloxane (D6) CAS 540-97-6

Cyclohexasiloxane (D6) – Volatile Cyclic Silicone for Cosmetic Formulations

Basic Information

• CAS Number: 540-97-6

• Molecular Formula: C₁₂H₃₆O₆Si₆

• Molecular Weight: 444.92 g/mol

• INCI Name: Cyclohexasiloxane

• Synonyms: Dodecamethylcyclohexasiloxane, D6

• Appearance: Clear, colorless, odorless liquid

• Density: ~0.97 g/cm³ (at 20°C)

• Boiling Point: ~245°C

• Viscosity: ~6–8 cSt (at 25°C)

• Volatility: Lower than cyclopentasiloxane (D5)

• Solubility: Insoluble in water; miscible with oils and organic solvents

• Storage: Store in tightly sealed containers in a cool, dry place, away from heat and direct sunlight

Overview
Cyclohexasiloxane (commonly referred to as D6) is a volatile cyclic silicone fluid widely used in cosmetic and personal care formulations. It serves as a texture enhancer, carrier, and spreading agent, facilitating even application of products on skin and hair. Its moderate volatility allows it to evaporate gradually after application, leaving a smooth, non-greasy, and residue‑free finish. It is considered safe and effective for use on skin and hair, making it a valuable ingredient in a wide range of products, including skin care, color cosmetics, deodorants, and hair conditioners.

Physicochemical Properties

• Volatile: Evaporates after application, leaving no residue.

• Excellent spreadability: Enhances the distribution of active ingredients and pigments.

• Non-greasy feel: Provides a light, silky skin feel without oiliness.

• Compatibility: Miscible with most oils, esters, and other silicones.

• Thermal stability: Stable under normal processing and storage conditions.

• Non-toxic and non-irritating: Well-tolerated by skin and eyes.

• Hydrophobic: Repels water, contributing to water resistance in certain formulations.

Mechanism of Action
In formulations, cyclohexasiloxane acts as a volatile carrier solvent. When applied, it spreads easily over the skin or hair, delivering active ingredients uniformly. It then evaporates at a controlled rate, leaving behind a thin, non-occlusive film of non-volatile ingredients (e.g., emollients, sunscreens, or pigments). This improves product performance while maintaining a light, fresh feel. Its lower volatility compared to D5 provides a longer working time during application.

Applications

• Skin care: Creams, lotions, serums, and sunscreens – improves spreadability, enhances absorption, and leaves a silky finish.

• Color cosmetics: Foundations, primers, and lipsticks – improves pigment dispersion, application, and long-wear properties.

• Hair care: Conditioners, serums, and styling products – reduces frizz, adds shine, and improves manageability without weighing hair down.

• Deodorants and antiperspirants: Provides a smooth, quick-drying application with a non-sticky finish.

• Other: Used as a carrier for fragrances and active ingredients.

Key Benefits

• Excellent spreadability and lubricity.

• Provides a light, non-greasy, silky skin feel.

• Evaporates gradually without leaving a residue.

• Enhances the delivery of active ingredients.

• Compatible with a wide range of cosmetic ingredients.

• Improves the texture, stability, and performance of formulations.

• Safe for use in leave-on and rinse-off products.

• Non-comedogenic and suitable for sensitive skin.

Recommended Use
Typical usage levels range from 1–30% of the formulation, depending on the desired volatility, spreadability, and sensory properties. For optimal performance, incorporate into the oil phase at room temperature or with gentle heating. Can be combined with other volatile and non-volatile silicones, oils, and emulsifiers for tailored formulations.

Safety and Handling

• Generally recognized as safe for use in cosmetics at recommended concentrations.

• Low irritation potential; well-tolerated by skin and eyes.

• Avoid contact with strong oxidizers.

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

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

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

Quality Assurance
Each batch is tested for purity, viscosity, and residual solvents to ensure consistent quality and compliance with cosmetic standards.