Frizz reads as the most visible hair problem and the most blamed on weather. The fuller picture sits one layer deeper. Frizz is what happens when the hair's outer surface (the cuticle) cannot hold moisture steady. The reasons it cannot hold moisture steady have less to do with the day's humidity than with the hair's porosity: how easily water passes in and out of the strand.
Once porosity is understood, the routine becomes simpler. Some hair benefits from sealing more, some from welcoming water more. The product mistakes that frustrate people for years are often porosity mismatches.
What porosity actually is
Every strand of hair has an outer cuticle of overlapping scales. When those scales lie flat and tight, water enters and leaves slowly. When they sit raised and loose, water enters and leaves easily.
Low-porosity hair has a tight cuticle. Water beads on it. Products can sit on top without absorbing. The hair often looks shiny but feels dry to the touch by mid-day. Heavy oils and butters tend to coat without penetrating.
Medium-porosity hair has a balanced cuticle. Most routines work without effort. This is the hair that "behaves" with whatever you do.
High-porosity hair has a raised cuticle. Water enters quickly and leaves quickly. The hair feels dry, looks frizzy, and tangles easily. Chemical processing (colour, bleach, perm, relaxer), heat damage, and natural variation all increase porosity.
The simplest porosity test
Take a clean strand of dry hair (one that has been washed and not styled). Drop it into a glass of room-temperature water. After three or four minutes:
- Floating at the top: low porosity. Water has not penetrated.
- Floating in the middle: medium porosity.
- Sinking to the bottom: high porosity. The strand is saturated quickly.
The test is approximate. It rules out the extremes, which is the part most worth knowing.
A routine for each porosity
Low porosity. Use warm water during washing to help the cuticle open and accept products. Pre-shampoo with a lightweight oil (jojoba, sweet almond, squalane) to soften the strand. Use lighter, water-based conditioners and leave-ins (humectants like glycerin, panthenol, hydrolysed proteins). Avoid heavy butter-based masks, which sit on top. A clarifying wash every two to four weeks prevents buildup.
Medium porosity. Most products work. The strategy is moderation, not specialisation. Conditioner mid-lengths to ends, occasional mask, and routine restraint.
High porosity. The cuticle needs help staying closed. Use cool-to-lukewarm water rather than hot. Use richer, oil-and-cream-based products that seal the cuticle: shea butter, mango butter, denser conditioners and leave-ins. Layer in this order: humectant for moisture, emollient for softness, occlusive for seal. Avoid over-washing, which strips natural oils that high-porosity hair badly needs.
A weekly bond-repair or protein treatment is often helpful for chemically-processed high-porosity hair. Used too often, protein can leave hair brittle; once every two to four weeks is the rule of thumb.
The role of humidity
In humid air, water vapour passes through the cuticle into the strand. In hair that absorbs water unevenly (high porosity), this swells some areas more than others and disrupts the strand's shape. Curls expand and lose definition; straight hair lifts and fuzzes. Low-porosity hair resists humidity better but, ironically, also resists the products that would help it stay smooth in the first place.
An anti-humidity serum or styling cream forms a thin film on the strand that slows water exchange. It is most useful for high-porosity hair on humid days. It does not stop weather; it slows its arrival into the strand.
The three habits that change the most
Cool final rinse. Helps close the cuticle after washing. Useful at all porosities; particularly worthwhile at high porosity.
Microfibre or cotton T-shirt towel. A rough terry-cloth towel lifts the cuticle and increases frizz. Squeezing with a softer fabric reduces both.
Detangle on damp, conditioned hair, with fingers or a wide-tooth comb. Dry brushing tears more strands and roughs up the cuticle further. A few minutes on damp, slippery hair removes tangles with the strand intact.
Frizz is rarely a willpower problem with your hair. It is usually a routine misaligned to the strand's porosity. The fix is one or two adjustments, not five new products.
Key takeaways
- Porosity is how easily water moves in and out of the hair strand.
- The float test is approximate but useful to rule out the extremes.
- Low porosity wants warmer water and lighter products; high porosity wants cooler water and richer ones.
- Cool final rinse, soft towel, gentle damp-hair detangling reduce frizz at every porosity.
- Chemically-processed hair is high-porosity; richer routines and periodic protein treatments help.
Common questions
Can porosity change?
Yes. Healthy hair you grow today is the porosity it inherits; the lengths shift higher in porosity as they age, are coloured, heat-styled, or weathered. A routine adjustment matters most for the lengths, because that is where porosity actually lives.
Are oils good for frizz?
For high-porosity hair, often yes, as a finishing seal. For low-porosity hair, often not, because the oil sits on top and weighs the strand without entering it.
Do I need a separate "anti-humidity" product?
If you live somewhere humid and have high-porosity hair, often yes. A leave-in or styling cream with film-forming ingredients (PVP, polyquaternium-types, certain silicones) helps stabilise the strand for the day. In dry climates the same product is usually unnecessary.
Should I use protein treatments?
Useful for chemically-processed and high-porosity hair every two to four weeks. Daily protein, or weekly heavy protein, can leave hair brittle. Watch how the hair feels after the third use; that is the signal worth listening to.
Cura is informational and not a substitute for medical advice. Sudden changes in hair texture or condition warrant a trichology or dermatology consultation.