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Cyclopentasiloxane

Cyclopentasiloxane suppliers and sourcing guide

Cyclopentasiloxane is a cyclic silicone made of five dimethylsiloxane units, a clear, odorless, volatile liquid that evaporates from skin and hair. It is made from dimethyldichlorosilane hydrolysis products, from which the cyclic fraction is separated and distilled. Cosmetic brands buy it as a volatile carrier for antiperspirants, hair serums, makeup and skin care, often blended with dimethicone or dimethicone gums.

See suppliersWhat to ask for on the COA
Also known as
Decamethylcyclopentasiloxane · D5 · Cyclomethicone 5 · CAS 541-02-6
Facts checked
November 2026

Forms and grades of cyclopentasiloxane

Suppliers sell different products under the same name. Specify the one you need.

  • Neat D5

    High-purity decamethylcyclopentasiloxane, sold with limits on D4 and D6 content.

  • Cyclomethicone blends

    Mixtures of D5 with D4 or D6, now less common because of restrictions on D4 in some markets.

  • Gum and elastomer blends

    D5 sold pre-blended with dimethicone gum or silicone elastomers as ready-made gels and serums.

  • D5-free replacements

    Volatile linear silicones and hydrocarbon or ester blends sold as alternatives where D5 is restricted.

What to check on the COA

Compare each result with your own specification when the lot arrives.

D5 assay
Purity by GC, with D4 and D6 reported separately.
D4 content
GC limit for octamethylcyclotetrasiloxane, which has tighter regulatory limits than D5 in some markets.
Volatility / evaporation
Distillation range or evaporation rate, which confirms the grade.
Water
Karl Fischer titration.
Refractive index and specific gravity
Physical constants for identity.

Storage, lots and expiry

Storage and shelf life

Store cyclopentasiloxane in tightly closed containers at room temperature, away from heat, sparks and open flame, since it is a combustible volatile liquid. Keep drums closed to limit evaporation losses. Shelf life is set by the supplier's specification, with a retest of assay and D4 content to extend it.

Lots and expiry dates

Record D5 assay and D4 and D6 results for each lot, and check them against the limits of each market you sell into, since some markets restrict cyclic siloxanes in finished products. Rotate FIFO.

Regulatory status

Facts from regulators and standards bodies, each linked to its source.

  • Health Canada's information sheet on siloxane D5 (CAS 541-02-6) states that the Government concluded D5 is not harmful to human health or the environment, after the 2009 assessment and the 2012 revised decision.

    Source: canada.ca (opens in a new tab)

  • The same information sheet notes that D5 was mainly used in products available to consumers, such as hair and skin products and antiperspirants.

    Source: canada.ca (opens in a new tab)

  • Health Canada's Natural Health Products Ingredients Database lists cyclopentasiloxane with non-medicinal purposes including solvent, for topical use only, citing CIR.

    Source: webprod.hc-sc.gc.ca (opens in a new tab)

This is general information, not regulatory advice. Status differs by country and by how the ingredient is used, so check the rules for your product and market.

Cyclopentasiloxane suppliers

Manufacturers and distributors whose own websites say they sell it.

We are checking cyclopentasiloxane suppliers now

Every listing is checked against the supplier’s own website before it goes live, so this list fills in over the coming weeks. The specs and COA checklist above are ready today.

Sell cyclopentasiloxane? Request a listing

Frequently asked questions

What forms of cyclopentasiloxane can brands buy?

Common forms include neat D5, cyclomethicone blends, gum and elastomer blends and d5-free replacements. Ask each supplier for the specification sheet of the exact grade they quote.

What should the COA for cyclopentasiloxane include?

Expect d5 assay, d4 content, volatility / evaporation, water and refractive index and specific gravity, each with its method, specification and result for that lot.

How should cyclopentasiloxane be stored?

Store cyclopentasiloxane in tightly closed containers at room temperature, away from heat, sparks and open flame, since it is a combustible volatile liquid. Keep drums closed to limit evaporation losses. Shelf life is set by the supplier's specification, with a retest of assay and D4 content to extend it.

What is the regulatory status of cyclopentasiloxane?

Health Canada's information sheet on siloxane D5 (CAS 541-02-6) states that the Government concluded D5 is not harmful to human health or the environment, after the 2009 assessment and the 2012 revised decision. The same information sheet notes that D5 was mainly used in products available to consumers, such as hair and skin products and antiperspirants. Health Canada's Natural Health Products Ingredients Database lists cyclopentasiloxane with non-medicinal purposes including solvent, for topical use only, citing CIR.

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