Cy
Cyclopentasiloxane
Cyclopentasiloxane · CyclomethiconeBarrier
Volatile silicone. Provides slip and a smooth finish; evaporates from the skin within minutes.
What it does
Cyclopentasiloxane is a small-molecule silicone that evaporates from the skin after application — it's the silicone behind the 'silky finish' of many makeup primers and moisturizers without leaving residue. Often paired with dimethicone, where the cyclopentasiloxane provides the application slip and dimethicone provides longer-lasting feel. EU regulators have flagged D5 in rinse-off products for environmental persistence; leave-on cosmetic use remains permitted.
Also known as
d5, cyclomethicone
Pairs worth knowing
This page is public and indexed on purpose (unlike profiles and drops, which are unlisted) — it’s the citation behind shared ingredient cards, and it should be findable.
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