What it is
Undecane is a straight-chain alkane (C11) frequently used together with tridecane as a light, fast-spreading hydrocarbon vehicle. It helps disperse other ingredients and leaves a light finish as the more volatile fraction evaporates. In sunscreens the undecane/tridecane pairing is valued for a light, smooth application feel.
Safety & warnings
Undecane is generally regarded as well tolerated as a light cosmetic hydrocarbon. It is not a recognized fragrance allergen; as a volatile solvent it can feel drying on very dry or sensitive skin if used at high levels.
Origin & sourcing
May be synthetic from petrochemicals or derived from renewable plant feedstocks; commonly supplied as a sugarcane-derived alkane blend with tridecane.
Questions everyone asks
Why are undecane and tridecane used together?
Combined, they create a light, fast-spreading vehicle that helps products apply smoothly and leaves a non-greasy finish.
Is undecane natural?
It can be plant-derived (commonly from sugarcane) or made from petrochemicals; both forms are used in cosmetics.