What Is C8-9 Isoalkane?
C8-9 Isoalkane is a blend of highly purified branched hydrocarbons that each contain eight or nine carbon atoms. Sourced from specific fractions of petroleum, it goes through hydrocracking and isomerization to create short, branched chains, then distillation removes impurities and narrows the carbon range. Formulators first turned to this ingredient in the 1990s as a cleaner, low-odor alternative to heavier mineral oils and traditional isoparaffins, and it quickly became a favorite for its light feel and quick evaporation.
You will find C8-9 Isoalkane in products where a fast-drying, non-greasy finish is needed, such as makeup removers, long-wear foundations, sunscreens, aerosol antiperspirants, hair sprays, cleansing oils, sheet masks, anti-aging serums and everyday moisturizers.
C8-9 Isoalkane’s Cosmetic Benefits/Uses
In formulas C8-9 Isoalkane serves two main jobs that help products perform and feel better on skin and hair:
- Solvent: It dissolves pigments, sunscreens, oils and other actives so they spread evenly, stay stable and leave a lightweight finish without greasy residue
- Viscosity controlling: By thinning heavy oils and waxes it fine-tunes thickness, making creams silkier, sprays more uniform and sticks glide smoothly
Who Can Use C8-9 Isoalkane
Because it is lightweight non-comedogenic and almost odorless C8-9 Isoalkane is generally suitable for all skin types including oily sensitive and mature skin. Dry skin may appreciate it as a non-greasy carrier that lets richer oils sink in while oily or acne-prone users like its quick-evaporating finish that does not leave residue. There are no specific skin types that need to avoid it unless an individual has a known sensitivity to hydrocarbons.
The ingredient is petroleum derived yet it contains no animal materials so it fits vegan and vegetarian preferences. Its sourcing does not involve animal testing in most major markets thanks to regulatory bans though shoppers should still check the finished brand’s cruelty-free stance.
No data show that topical C8-9 Isoalkane poses risk to pregnant or breastfeeding women when used in normal cosmetic concentrations. This is not medical advice and anyone expecting or nursing should run all products by a healthcare professional to be safe.
C8-9 Isoalkane does not make skin more sensitive to sunlight and it is often paired with sunscreens to improve spread. One practical note: it is flammable in aerosol form so keep such products away from open flames.
Potential Side Effects/Adverse Reactions
Reactions to C8-9 Isoalkane differ from person to person. The issues listed below are possible but uncommon when the ingredient is used at the low levels found in cosmetics that have been formulated correctly.
- Mild skin irritation such as temporary redness stinging or burning
- Contact dermatitis in individuals allergic or highly sensitive to hydrocarbon solvents
- Eye irritation if a spray or liquid accidentally enters the eyes
- Dry or tight feeling in very dehydrated skin due to its fast evaporation
- Inhalation discomfort like coughing when aerosol products are used in poorly ventilated areas
If any of these effects occur stop using the product and seek advice from a medical professional.
Comedogenic Rating
Rating: 0 / 5 C8-9 Isoalkane has a very small molecular size and evaporates quickly instead of sitting on the surface so it does not clog pores or trap dead cells and sebum. Studies and anecdotal reports show it behaves more like a volatile silicone than a heavy oil which keeps the rating at the very bottom of the scale. This makes it a friendly choice for people who are prone to acne or breakouts, though the finished formula’s other ingredients still matter. In aerosol or wipe formats it flashes off even faster which further lowers any pore-blocking risk.
Summary
C8-9 Isoalkane works mainly as a solvent and viscosity controller. It dissolves pigments UV filters and oily actives letting them spread evenly and stay stable, then it thins thick creams or waxes so textures feel lighter and glide better. Its rapid evaporation leaves a weightless finish that many brands market as non-greasy or long-wear.
Although it rarely makes headlines the ingredient is popular behind the scenes in long-wear makeup cleansing oils sunscreens and aerosol sprays where formulating challenges demand a light fast-drying hydrocarbon. Safety data show very low irritation and no proven systemic toxicity at cosmetic use levels so it is considered safe for daily application across all skin types. As with any new product it is wise to run a simple patch test first just to ensure your skin agrees with the overall formula.