Dodecamethylcyclohexasiloxane (D6)
- Silicones
- CAS 540-97-6
- IUPAC: 2,2,4,4,6,6,8,8,10,10,12,12-dodecamethyl-1,3,5,7,9,11,2,4,6,8,10,12-hexaoxahexasilinane
Dodecamethylcyclohexasiloxane (D6) (CAS 540-97-6) appears in 2 of the 1,812 car-care products CarCareTruth tracks (as of June 2026). It is classified as a VOC.
Low acute human toxicity. Not GHS-classified as a health hazard at mixture-level concentrations typically encountered in consumer spray products. Physical hazard only (combustible/flammable at pure substance level).
Dodecamethylcyclohexasiloxane (D6) is a six-membered cyclic volatile methylsiloxane (cVMS), closely related to D5 (the five-membered ring analog). It is used as a secondary carrier solvent in silicone-based automotive sealants, glazes, and leave-on coatings — typically at concentrations of 1–5% alongside a larger D5 fraction.
Environmental concern: D6, like D5, is on the ECHA SVHC candidate list for vPvB (very persistent, very bioaccumulative) properties under EU REACH. It is not readily biodegradable and accumulates in aquatic sediments with long environmental half-lives. D6 is not classified as PFAS under US EPA definitions. In automotive spray sealants D6 is a minor component (secondary to D5), so its environmental contribution at the product level is proportionally small.
Human health: At the pure-substance level D6 carries a combustible liquid physical hazard classification. At the concentrations used in consumer spray products (1–5%), no GHS health hazard classification propagates to the mixture. D6 is not an asthmagen, not Prop 65 listed, and has no known sensitization hazard.
Health & environment profile
- VOC
- yes
- Prop 65 listed
- no
- Asthmagen
- no
- EPA Safer Choice
- no
- Aquatic toxicity
- no
- Biodegradable
- no
- Bioaccumulative
- yes
- Persistent
- yes
- Ozone depleting
- no
- Microplastic
- no
- PFAS
- no
- Env. score
- 3/5
Common questions about Dodecamethylcyclohexasiloxane (D6)
- What is Dodecamethylcyclohexasiloxane (D6) used for in car care?
- Volatile cyclic siloxane co-carrier; secondary delivery solvent in silicone-based sealants and glazes alongside D5
- Is Dodecamethylcyclohexasiloxane (D6) a VOC?
- Yes. Dodecamethylcyclohexasiloxane (D6) is classified as a volatile organic compound (VOC).
- Is Dodecamethylcyclohexasiloxane (D6) on California's Proposition 65 list?
- No. Dodecamethylcyclohexasiloxane (D6) is not on California's Proposition 65 list.
2 products contain this
Optimum Gloss-Coatceramic-coating
Related
Health and environment notes translate the manufacturer Safety Data Sheet, the GHS classification, and authoritative regulatory listings (California Prop 65, EPA). Not medical advice. They describe the ingredient itself; whether a hazard applies to a finished product depends on its concentration and how it's used.