Cyclopentasiloxane (D5)

✦ Delivers an ultra-lightweight, non-greasy silky feel that evaporates cleanly from the skin
✦ Functions as a volatile carrier and spreading agent for actives, pigments, and heavier silicones
✦ Provides instant detangling, shine, and frizz control in hair care formulations
✦ Excellent solvent for sunscreen filters, fragrance oils, and dimethicone blends
✦ Enhances product spreadability in primers, serums, and antiperspirant sticks
✦ Leaves no residue after evaporation, making it ideal for matte-finish and fast-absorbing products
✦ Synthetically derived cyclic silicone with high purity and consistent cosmetic-grade performance

Cyclopentasiloxane, commonly referred to as D5, is a cyclic volatile methylsiloxane that has been a cornerstone of modern cosmetic formulation since the late 20th century. Originally developed as part of the broader silicone chemistry family by companies like Dow Corning, D5 rapidly became the industry-standard volatile carrier due to its unique combination of low viscosity, clean evaporation, and sensory elegance. It is found in thousands of commercial products ranging from prestige skincare serums to mass-market hair treatments.

What makes Cyclopentasiloxane exceptional is its volatility paired with outstanding spreading properties. Unlike heavier silicones such as dimethicone, D5 evaporates completely at skin temperature, depositing only the active ingredients or heavier silicone films it was blended with. This mechanism allows formulators to create products that feel weightless on application yet deliver lasting conditioning or protective benefits from the non-volatile components left behind.

Rabibazaar supplies cosmetic-grade Cyclopentasiloxane (D5) suitable for DIY beauty formulators, independent skincare brands, hair care developers, and professional cosmetic chemists.

INCI Name : Cyclopentasiloxane
Chemical Name : Decamethylcyclopentasiloxane
CAS Number : 541-02-6
Molecular Formula : C10H30O5Si5
Appearance : Clear, colorless liquid
Odor : Virtually odorless
pH (1% solution) : Not Applicable (non-aqueous)
Solubility : Insoluble in water; miscible with most silicones and cosmetic oils
Specific Gravity : 0.950 to 0.960 at 25°C
Flash Point : 77°C (closed cup)
HLB Value : Not Applicable
Recommended Use Level : 1% to 50% depending on product type
Type : Volatile cyclic silicone / Emollient / Carrier
Shelf Life : 24 months when stored properly in sealed containers

Skincare (Serums, Primers, Lotions) ★★★★★
D5 is the gold-standard carrier for lightweight facial serums and silicone-based primers. Use at 10% to 40% as the volatile phase to deliver actives while leaving a dry, velvety finish.

Haircare (Serums, Leave-In Treatments, Heat Protectants) ★★★★★
Provides immediate slip, shine, and frizz control without weighing hair down. Use at 20% to 50% in hair serums blended with dimethicone or phenyl trimethicone for lasting smoothness.

Antiperspirants and Deodorants ★★★★★
Functions as the primary volatile carrier in stick and roll-on antiperspirant formulations. Use at 30% to 50% to dissolve aluminum salts and provide a dry, non-sticky application feel.

Body Care (Dry-Touch Lotions, Body Sprays) ★★★★☆
Excellent for creating fast-absorbing, non-greasy body lotions and mist sprays. Use at 5% to 20% to improve spreadability and reduce the tacky feel of glycerin-heavy formulations.

Color Cosmetics (Foundations, Primers, Setting Sprays) ★★★★★
Acts as the carrier and pigment dispersant in liquid foundations and makeup primers. Use at 15% to 40% to achieve even pigment distribution and a smooth, matte finish on skin.

In my formulation work, I rely on Cyclopentasiloxane as the workhorse volatile phase whenever I need a product to feel weightless on skin but still deposit functional ingredients. The key to working with D5 is understanding that it is not the active — it is the delivery vehicle. Pairing it with a small percentage of high-molecular-weight dimethicone or dimethiconol creates the classic "silicone serum" architecture where D5 evaporates and leaves behind a smooth, non-migrating conditioning film.

ADVANCED TIP: For a professional-grade hair serum, blend 60% Cyclopentasiloxane with 8% Dimethiconol (high viscosity grade), 2% Phenyl Trimethicone for added refractive shine, and a trace of Tocopheryl Acetate as antioxidant. Mix at room temperature with moderate stirring until homogeneous. The D5 evaporates post-application, depositing only the conditioning silicones onto the hair shaft without buildup associated with non-volatile silicones alone.

Normal Skin : ★★★★★ — Evaporates cleanly, leaving a smooth, non-greasy finish ideal for daily use.
Dry Skin : ★★★★☆ — Excellent carrier for heavier emollients but provides no lasting moisture on its own.
Oily Skin : ★★★★★ — Volatile nature means zero residue, making it perfect for matte and oil-free formulations.
Combination : ★★★★★ — Adapts well across zones since it evaporates without contributing oiliness or dryness.
Sensitive Skin : ★★★★☆ — Generally well tolerated and non-irritating, though patch testing is advised for silicone-sensitive individuals.
Mature Skin : ★★★★☆ — Good carrier for anti-aging actives but does not provide occlusive moisture retention on its own.
Acne-Prone : ★★★★★ — Non-comedogenic and leaves no pore-clogging residue after evaporation.

CONCEPT 1: Velvet Matte Primer Serum
Usage Level : 35%
Key Ingredients: Cyclopentasiloxane, Dimethicone Crosspolymer, Silica Microspheres, Tocopheryl Acetate
Result : A weightless, pore-blurring primer that creates a matte velvet canvas for makeup application.

CONCEPT 2: Instant Shine Hair Serum
Usage Level : 55%
Key Ingredients: Cyclopentasiloxane, Dimethiconol, Phenyl Trimethicone, Argania Spinosa Kernel Oil
Result : A lightweight, non-greasy hair serum that tames frizz and delivers mirror-like shine without buildup.

CONCEPT 3: Dry-Touch Body Mist Lotion
Usage Level : 15%
Key Ingredients: Cyclopentasiloxane, Caprylic/Capric Triglyceride, Cyclohexasiloxane, Allantoin
Result : A fast-absorbing, spray-on body lotion with a silky dry finish suited for hot and humid climates.

INCI Declared : Yes — required on all cosmetic labels
EU Cosmetics Reg : Restricted — regulated under EC 2024/996 amending Annex II; restricted in wash-off products above 0.1% D5 concentration in the EU
Rinse-Off Limit : 0.1% maximum in EU (as of January 2020 restriction, further tightened 2024)
Leave-On Limit : Currently permitted in leave-on products in the EU; ongoing ECHA review
Allergen Alert : No — not a recognized allergen
Skin Safety : Safe at recommended levels; non-irritating and non-sensitizing in standard patch testing
Eye Area Use : Use with caution — avoid direct contact with eyes
Ingestion : Not for internal use
Pregnancy Use : Safe — no evidence of systemic absorption at cosmetic use levels
Child Safety : Safe for use in products for children above 3 years at standard cosmetic levels
Ventilation : Recommended — volatile solvent; avoid prolonged inhalation in enclosed mixing areas
Storage : Cool dry place away from heat sources and open flames; keep container tightly sealed
Container : HDPE or PET recommended; glass acceptable; avoid prolonged contact with rubber seals

⚠️ EU regulatory status for D5 has evolved significantly. As of 2024, D5 is restricted in wash-off cosmetic products at concentrations above 0.1% in the EU. Formulators selling into or sourcing from EU markets should verify the latest Annex II entry and any pending ECHA restrictions on leave-on applications. Pakistan-market formulations are not subject to EU limits but awareness is recommended for export readiness.

Working pH Range : Not Applicable (non-aqueous; pH-independent)
Heat Stability : Stable up to 150°C; however, evaporates readily above 100°C so add during cool-down if retention in final product is desired
Freeze-Thaw Stable : Yes — remains liquid well below 0°C
Emulsion Type : W/Si (water-in-silicone) or used as volatile phase in O/W and W/O systems
Emulsification Phase: Can be added in hot or cold phase depending on formulation type
Compatible With : Dimethicone, phenyl trimethicone, most volatile and non-volatile silicones, cosmetic esters, mineral oil, organic sunscreen filters
Incompatible With : Strong oxidizing agents; may swell certain rubber and elastomer components; not compatible with water without appropriate emulsifier
Oxidation Risk : Low — chemically inert silicone backbone resists oxidation
Discoloration Risk : None — colorless and does not yellow over time under normal storage
Formulation Notes : D5 evaporates during processing if heated in open vessels. When formulating emulsions, add D5 to the silicone phase and emulsify at moderate shear. For maximum retention in finished products, incorporate during the cool-down phase below 40°C.

Q: What does Cyclopentasiloxane do in cosmetic products?
A: It acts as a lightweight volatile carrier that spreads products evenly across skin or hair and then evaporates, leaving behind only the active or conditioning ingredients. It gives products a silky, dry-touch feel without greasiness.

Q: Is Cyclopentasiloxane safe for skin and hair?
A: Yes, D5 has been extensively safety-tested and is considered non-irritating, non-sensitizing, and non-comedogenic at cosmetic use levels. It does not penetrate the skin in meaningful amounts and evaporates from the surface.

Q: Will Cyclopentasiloxane cause hair buildup?
A: No. Because D5 is volatile, it evaporates completely after application. Any buildup in silicone-based hair products comes from the non-volatile silicones like dimethicone that D5 carries and deposits, not from D5 itself.

Q: Can I use Cyclopentasiloxane in water-based formulations?
A: D5 is not water-soluble, so you need a silicone-compatible emulsifier such as PEG-10 Dimethicone or Cetyl PEG/PPG-10/1 Dimethicone to incorporate it into water-based creams or lotions. It blends easily into anhydrous and silicone-phase formulations without an emulsifier.

Q: How does Cyclopentasiloxane compare to Cyclohexasiloxane (D6)?
A: D5 evaporates faster than D6, giving a lighter, more fleeting sensory feel. D6 has a slightly slower evaporation rate, which some formulators prefer for products needing a longer wet-slip working time. D5 is more commonly used due to wider availability, but blending D5 with a small amount of D6 can fine-tune the evaporation profile.

Product evaluation

Review the specifications, supplied grade, intended use and compatibility of Cyclopentasiloxane (D5) before ordering for production. Test a small quantity in the actual application and document the result before scaling.

Quality control

Inspect the received batch for expected appearance, odor, texture, packaging condition and labeling. Keep supplier and batch records, use accurate measurements, and retain a reference sample when the material is used commercially.

Storage and responsible use

Store tightly closed in a clean, cool and dry location away from direct sunlight. Follow the current supplier instructions and all safety, labeling and regulatory requirements that apply to the intended finished product.