Isododecane

Overview

Isododecane is a branched 12-carbon hydrocarbon. It used to be made from petroleum; today most cosmetic-grade isododecane is plant-derived (from sugarcane fermentation, branched and hydrogenated to the target structure), which puts it inside the “naturally-derived” category despite being a precisely defined synthetic-feeling molecule.

It looks and feels like cyclomethicone — a clear, water-thin, almost odourless liquid with intense slip and a fast dry-down. The difference is the chemistry: isododecane is a hydrocarbon, not a silicone, so it sidesteps every silicone regulatory and marketing concern (no D4/D5 watchlist issues, no silicone-free messaging conflict, no rinse-off restriction in the EU).

That makes isododecane the go-to substitute when a formulator wants the cyclomethicone feel without the cyclic silicone story.

Shelf life is 2-3 years. It is chemically inert and does not oxidise.

What it does in a formula

The defining behaviour: instant slip, fast dry-down, powder finish. A drop on the back of the hand feels almost wet, spreads to nothing in 20 seconds, and leaves behind a powdery rather than oily sensation.

Specifically:

• Volatile carrier — evaporates from skin and lip products at body temperature, leaving the heavier ingredients behind
• Solvent for waxes and pigments — dissolves cosmetic waxes, oil-soluble dyes, and some UV filters
• Long-wear behaviour — when paired with a film-former, isododecane evaporates and locks the film in place, which is why every long-wear matte lipstick and tattoo-style brow product uses it
• Light primer feel — gives a “blurring” optical effect on its own

Like cyclomethicone, it does not deliver active skin benefits. It is a vehicle, and its job is to deliver other ingredients evenly and then disappear.

How to use

Add to the cool-down phase, below 40 C. Isododecane has a boiling point around 175 C but begins evaporating noticeably above 50 C, especially in open vessels. Always add cool.

Usage rates by product type:

• Long-wear matte lipsticks: 20-50% (the bulk of the formula)
• Long-wear foundations and concealers: 10-30%
• Primers and mattifiers: 10-30%
• Setting sprays: 5-15%
• Hair styling products (non-aerosol): 5-15%
• Brow gels and lash primers: 20-40%
• Sunscreen sticks: 5-15%
• Body sprays and quick-dry oils: 10-30%

It blends well with light esters, silicones (if you use them), and waxes for stick products.

Best for / Worst for

Best for: long-wear makeup, mattifying primers, quick-drying body sprays, hair styling sprays that need to feel light, stick deodorants formulated without cyclomethicone, EU-compliant volatile emollient applications, brands marketing as silicone-free but wanting silicone-style feel.

Worst for: moisturising claims (it evaporates and leaves nothing), products that need any kind of long-lasting emollient feel, anhydrous balms meant to sit on the skin (it disappears too fast).

Common pitfalls

Heating it. A 70 C emulsification will evaporate 20-40% of your isododecane. Always add at the cool-down stage with the container partially covered.

Treating it as moisturising. It is a delivery vehicle. Remove it from a formula and the heavy ingredients remain — the texture changes drastically but the skincare claims survive. The opposite is true if you remove the active ingredients and keep the isododecane: you get a nice-feeling but inert product.

Overusing it in a leave-on cream. Above 20% in a face cream, the product feels slightly “thinning” — like it disappears before the customer feels they have moisturised. For face creams, 5-10% is plenty.

Storage in open containers. Isododecane evaporates from an open bottle within days to weeks. Keep sealed.

Substitutes

• Cyclomethicone (cyclopentasiloxane) — closest match for feel and behaviour, but with EU regulatory concerns in rinse-off products.
• Isohexadecane — close relative, slightly less volatile, slightly more cushioning.
• Hydrogenated polydecene — synthetic hydrocarbon with similar light feel but non-volatile (it stays put).
• Tridecane / Cetiol Ultimate — newer volatile hydrocarbons, similar role.
• Light ethanol — for cheap setting sprays; drying on skin.