Cyclohexasiloxane.

What it does

It is a light, colourless, odourless fluid that gives products an instant silky, non-greasy slip and good spreadability, then evaporates off the skin or hair leaving little residue. It is used as a carrier/solvent and for that smooth feel, often alongside heavier silicones.

Benefits

• Light, silky, non-greasy feel with excellent spreading
• Volatile, so it evaporates rather than leaving an oily or built-up residue
• Good carrier/solvent for thinning heavier silicones and oils
• Low acute toxicity and not a skin irritant or sensitiser in testing

Side effects

• Very low skin irritancy; the main concerns are environmental, not topical
• D6 is persistent and bioaccumulative (PBT), and the EU has moved to cap it at 0.1% in cosmetics
• Risk-assessment work has flagged cumulative exposure from multiple leave-on products at high D6 levels as worth monitoring

Who it's for

Most skin and hair types; found in creams, deodorants, sun care and makeup for a light, smooth finish