Cyclopentasiloxane (D5) 250 g

Lightweight Volatile Silicone for Smooth, Silky Cosmetic Formulations

Cyclopentasiloxane, also known as D5 or Decamethylcyclopentasiloxane, is a volatile cyclic silicone traditionally used in cosmetic and personal-care formulations to provide excellent spreadability, slip and a lightweight silky sensory profile.

Unlike heavier non-volatile silicone fluids, Cyclopentasiloxane spreads easily across the skin or hair and gradually evaporates after application.

This can help produce a:

• Lightweight feel
• Silky texture
• Dry-touch finish
• Smooth application
• Reduced greasy sensation
• Improved product spreadability

What Is Cyclopentasiloxane?

Cyclopentasiloxane is a cyclic silicone composed of repeating silicon-oxygen units.

INCI Name: Cyclopentasiloxane
Chemical Name: Decamethylcyclopentasiloxane
Abbreviation: D5
CAS Number: 541-02-6
EC Number: 208-764-9
Form: Clear, Colorless Liquid
Primary Characteristic: Volatile Silicone

It has a low surface tension, which allows cosmetic formulations to spread rapidly and evenly over skin and hair.

Main Cosmetic Functions

Depending on the formulation, Cyclopentasiloxane has historically been used as a:

• Emollient
• Solvent
• Spreading agent
• Hair-conditioning ingredient
• Antistatic ingredient
• Viscosity-modifying ingredient
• Volatile carrier
• Sensory modifier

Its most recognizable benefit is its ability to create a silky, non-heavy application feel.

Volatile Silicone Technology

Cyclopentasiloxane does not behave like a conventional vegetable oil.

After application, a substantial portion of the ingredient gradually evaporates.

This makes it useful for formulations designed to feel:

• Less oily
• Less heavy
• More elegant
• Faster drying
• Smoother during application

For technical accuracy, Cyclopentasiloxane should generally be described as evaporating, rather than being rapidly absorbed by the skin.

Use in Hair-Care Formulations

Cyclopentasiloxane has traditionally been widely used in:

• Hair serums
• Anti-frizz products
• Hair oils
• Leave-in products
• Hair styling products
• Heat-protection formulations

It can act as a lightweight carrier for other silicone ingredients and conditioning materials.

Possible sensory benefits include:

• Easier spreading
• Increased slip
• Smoother hair feel
• Improved shine
• Reduced heavy or greasy sensation

It should not be described as permanently repairing damaged hair.

Use in Hair Serums

One traditional application is silicone-based hair serum.

Cyclopentasiloxane can be combined with compatible ingredients such as:

• Dimethicone
• Dimethiconol
• Phenyl Trimethicone
• Selected cosmetic esters
• Oil-soluble fragrance

to produce a lightweight serum system.

As the D5 evaporates, the less volatile conditioning materials remain on the hair.

Use in Skincare

Cyclopentasiloxane has also historically been incorporated into:

• Face creams
• Facial serums
• Primers
• Body lotions
• Lightweight moisturizers
• Hand-care products

It can improve product spreadability and reduce the heavy feel of richer oil phases.

However, current and future regulatory restrictions must be considered before developing new products.

Use in Makeup

Cyclopentasiloxane has been particularly popular in color cosmetics such as:

• Makeup primers
• Foundations
• BB creams
• Concealers
• Long-wear formulations

because it helps formulas spread quickly and evenly.

It may contribute to:

• Silky application
• Lightweight feel
• Improved pigment distribution
• Dry-touch sensory profile

Is Cyclopentasiloxane a Moisturizer?

Cyclopentasiloxane should not primarily be described as a moisturizer.

Its main cosmetic benefits are related to:

• Sensory modification
• Emolliency
• Slip
• Spreadability
• Volatile carrier properties

For true humectant moisturization, ingredients such as glycerin may be more appropriate.

Is Cyclopentasiloxane Water-Soluble?

No.

Cyclopentasiloxane is not soluble in water.

It is compatible with many:

• Silicones
• Cosmetic esters
• Oil-phase ingredients
• Selected fragrance materials

In water-containing creams or lotions, an appropriate emulsification or silicone-emulsification system may be required.

Use in Soap

Cyclopentasiloxane should not be promoted as a conventional soap-making ingredient.

Traditional soap is produced through the saponification of oils with sodium hydroxide or potassium hydroxide.

Cyclopentasiloxane:

• Does not participate in saponification
• Does not replace soap-making oils
• Does not replace NaOH or KOH
• Is not necessary for traditional cold process soap

More importantly, regulatory restrictions significantly limit its use in wash-off products in the European Union.

Important EU Restriction for Soap & Rinse-Off Cosmetics

In the European Union, Cyclopentasiloxane (D5) has been restricted in wash-off cosmetic products since:

31 January 2020

D5 must be present at less than 0.1% by weight in such products.

Wash-off products include products that are normally rinsed away with water after application.

Examples include:

• Soap
• Shampoo
• Shower gel
• Facial cleanser
• Rinse-off conditioner

Therefore, recommendations such as:

“Use Cyclopentasiloxane at 1–5% in soap”

are not appropriate for EU-market rinse-off cosmetics.

Upcoming EU Restriction for Leave-On Cosmetics

Under Commission Regulation (EU) 2024/1328, the restriction will also apply to cosmetic products other than wash-off products after:

6 June 2027

From that date, D5 may not be placed on the EU market in these cosmetic products at a concentration equal to or greater than:

0.1% by weight

This affects traditional D5 applications such as:

• Hair serums
• Makeup primers
• Foundations
• Leave-in hair products
• Skin serums
• Leave-on creams

For new products intended for the European market, formulators should therefore consider alternative technologies.

Regulatory Status Depends on Market

Requirements for Cyclopentasiloxane differ between countries and regions.

Always check regulations applicable to the intended market, including:

• European Union
• Türkiye
• United Kingdom
• United States
• Gulf countries
• Asian markets
• Other export markets

A concentration suitable in one market may not be permitted in another.

Why Is D5 Restricted in the EU?

The EU restriction is primarily associated with the environmental properties of cyclic siloxanes.

D5 has been identified as a substance of environmental concern because of its very persistent and very bioaccumulative properties.

The restriction therefore does not simply mean that Cyclopentasiloxane was found to be inherently unsafe for normal skin contact.

The environmental release of the material is a major regulatory consideration.

Cosmetic Safety

The Scientific Committee on Consumer Safety previously concluded that D5 was safe at the cosmetic concentrations evaluated, with exceptions including certain aerosol applications.

Professional formulators should distinguish between:

• Consumer cosmetic safety
• Environmental restrictions
• Market-specific legal requirements

These are separate considerations.

Spray Applications

Special care should be taken with aerosolized and spray products.

Inhalation exposure can substantially alter safety assessment.

The SCCS previously expressed specific concerns regarding certain:

• Hair styling aerosols
• Sun-care spray products

For this reason, do not automatically transfer usage levels from non-spray formulations into aerosol or spray applications.

Processing

Cyclopentasiloxane is volatile.

For formulations in markets where its use is legally permitted, unnecessary heating should generally be minimized.

A practical processing approach may include:

1. Prepare the main formulation.
2. Cool the batch where necessary.
3. Add Cyclopentasiloxane during an appropriate lower-temperature stage.
4. Mix in a covered vessel where practical.
5. Minimize prolonged exposure to heat and open air.

The exact process should follow the formulation and supplier TDS.

Volatility During Manufacturing

Because Cyclopentasiloxane evaporates relatively easily:

• Keep containers closed.
• Avoid unnecessary heating.
• Avoid long open-vessel mixing.
• Minimize excessive air movement over the product.

Loss through evaporation can change the actual composition of the finished formulation.

Typical Historic Usage Levels

Historically, Cyclopentasiloxane has been used at levels substantially above 0.1% in various leave-on products.

However, because regulatory limits are changing, historic usage ranges should not be treated as current universal recommendations.

For products intended for sale today, determine the allowed concentration according to:

• Product type
• Target country
• Date the product will be placed on the market
• Applicable environmental restrictions

Cyclopentasiloxane Alternatives

For new European formulations, manufacturers may consider alternative volatile or dry-touch emollient systems.

Possible categories include:

• Lightweight cosmetic esters
• Volatile hydrocarbons permitted for cosmetic use
• Silicone alternatives
• Hemisqualane-type emollients
• Low-viscosity natural-origin emollients

No single ingredient necessarily reproduces all properties of D5.

Replacement systems should be evaluated for:

• Spreadability
• Evaporation profile
• Dry-touch effect
• Compatibility
• Pigment wetting
• Hair feel
• Stability

Cyclopentasiloxane vs. Dimethicone

These two silicones behave differently.

Cyclopentasiloxane

• Volatile
• Lightweight
• Evaporates after application
• Excellent spreading agent
• Dry, silky sensory profile

Dimethicone

• Generally non-volatile
• Remains on the skin or hair
• Provides conditioning and film-forming effects
• Available in many viscosities

They should not automatically be treated as interchangeable ingredients.

Product Details

Product Name: Cyclopentasiloxane
INCI Name: Cyclopentasiloxane
Chemical Name: Decamethylcyclopentasiloxane
Abbreviation: D5
CAS Number: 541-02-6
EC Number: 208-764-9
Weight: 250 g
Form: Clear, Colorless Liquid
Primary Functions: Volatile Carrier / Emollient / Solvent / Spreading Agent / Sensory Modifier
Water Solubility: Insoluble
Applications: Professional Cosmetic Formulation, subject to local regulatory restrictions

pH Information

Cyclopentasiloxane is an essentially anhydrous silicone fluid.

For this reason, assigning a general specification such as:

pH 5.0–7.0

to the raw material is not particularly meaningful.

The pH of the complete water-containing finished product should instead be measured.

Purity

Only describe the product as:

100% Pure Cyclopentasiloxane

if the supplier COA confirms this.

Commercial silicone fluids may contain:

• D5
• D6
• Other cyclic siloxanes
• Trace impurities

This is especially important because EU restrictions apply separately to specified cyclic silicones.

Professional users should review:

• COA
• SDS
• TDS
• D4/D5/D6 profile
• Purity
• Regulatory declaration

before formulation.

Safety Information

Cyclopentasiloxane is a professional cosmetic raw material.

During handling:

• Avoid eye contact.
• Avoid ingestion.
• Avoid unnecessary inhalation of vapor or mist.
• Do not aerosolize without an appropriate safety assessment.
• Work with suitable ventilation.
• Keep away from ignition or heat sources according to the SDS.
• Follow the supplier’s SDS and TDS.
• Verify regulatory compliance before commercial use.

Storage

Store Cyclopentasiloxane:

• In tightly closed packaging
• In a cool and dry location
• Away from excessive heat
• Away from direct sunlight
• Protected from unnecessary evaporation
• Away from contamination

Keep containers closed immediately after dispensing.

Wholesale & Professional Raw Material Supply

We supply Cyclopentasiloxane and other cosmetic silicones, emollients, esters and formulation raw materials in wholesale quantities for laboratories, cosmetic manufacturers, formulators and professional product developers.

Because regulatory restrictions on D5 vary by market and product category, customers should specify:

• Target market
• Intended application
• Required quantity
• Product format
• Expected launch date

before developing a commercial formulation.

We also provide private label and contract manufacturing services for skincare, hair-care and personal-care products using ingredients and technologies compliant with the intended target market.

For new European-market projects, alternative D5-free sensory systems can be evaluated where appropriate.