Frizz

Key takeaways

• Frizz combines fibres standing away from the hair mass, rough surface friction and moisture uptake. It is worse with a damaged cuticle, which is why bleached, relaxed and heat-damaged hair frizzes more. Sinclair 2007
• Humidity matters through measurable physics. In an industry study, hair water content rose linearly with relative humidity between 40% and 85%, and the fibre lost stiffness as it did. Gao 2007
• Frizz is also tactile. A 2021 L'Oreal-led study found humidity changes the friction of curly hair, which may change how frizzy it feels by touch. Skedung 2021
• Anti-frizz products work by lowering friction (silicone, oil, cationic conditioning) and by making the surface less water-attracting. In one supplier study, a shampoo with polyquaternium-70 beat polyquaternium-10 and guar for humidity resistance. Gao 2007
• Reducing damage (less bleach, heat and rough towelling) lowers frizz at the source. Products only manage it.

The science

Surface: bleaching removes the fatty outer layer, raises wettability and friction, and gives the straw-like feel. Re-lubricating with a conditioner restores water repellency and cuts combing work. Liu 2022

Water: Gao defined a humidity-resistance factor from fibre stiffness at 50% versus 80% relative humidity. A value above 1 means a product reduces the humidity effect, which is what "anti-frizz" means. It is an industry method, checked against image analysis in the same paper. Gao 2007

What it means for your hair

• Curl 3A-4C is most affected by humidity on touch, according to the friction study. Moisture plus sealing styling products help.
• High-porosity hair takes up and loses water fast, so it frizzes in humidity. Film-forming products help (see porosity).
• Fine straight hair: frizz is usually flyaways from static or damage. Use a light conditioner.
• Low-porosity hair: frizz is more often heavy product residue than moisture (inference).

Myths and facts

• Myth: "Humidity always causes frizz." The effect is real but depends on hair type and condition.
• Myth: "Sulfate-free shampoo prevents frizz." We found no trial.
• Myth: "Oils fix frizz." Oils reduce surface friction (see oils and hair), but their effect on water uptake varies.

Bottom line

Condition at every wash and apply a leave-in (silicone or an oil or cream) to damp hair. Handle wet hair gently, limit heat and avoid unnecessary bleach or relaxer. If humidity is your trigger, look for cationic polymers (polyquaternium, guar) and silicones (see silicones). Trim damaged ends (see split ends).