Air drying and blow drying compared

Heat damages hair, so avoiding heat should be better. That reasoning is sound as far as it goes, but it treats wetness as neutral, and wetness is not neutral.

Wet hair is swollen and in its most fragile state. It stretches considerably further before breaking, its cuticle is lifted, and it is far more vulnerable to mechanical damage. Hair left wet for hours spends hours in that condition.

Every time hair gets wet it swells, and as it dries it contracts. Repeated often enough and held long enough, this cycle stresses the cuticle. The term for the cumulative effect is hygral fatigue.

It matters most for high-porosity hair, which absorbs and releases water fastest and swells most. For that hair type, sitting wet for three hours is not a neutral choice.

1. 01Squeeze out as much water as you can with your hands before touching a towel.
2. 02Blot and squeeze with an old cotton t-shirt or microfibre towel rather than rubbing with terry cloth.
3. 03Apply your leave-in or oil now, while hair is damp, so the barrier is in place as it dries.
4. 04Let hair hang loose rather than tying it up wet, which keeps it wet far longer.
5. 05Do not brush it while soaking. Detangle with a wide-tooth comb, from the ends up, or before washing.
6. 06Aim to be substantially dry within an hour or two rather than four.

1. 01Remove as much water as possible first. Drying from soaking wet takes far longer and applies far more total heat.
2. 02Apply a heat protectant.
3. 03Use a medium or cool setting rather than maximum. Cool takes longer but costs much less.
4. 04Keep the dryer moving and at a distance of at least fifteen to twenty centimetres.
5. 05Point the airflow down the length of the hair, following the cuticle direction, which reduces roughing.
6. 06Stop when hair is dry. Continuing past that point is pure damage with no styling benefit.

A diffuser is worth having if your hair is wavy or curly. It disperses airflow so it dries the hair without blasting the pattern apart.

A reasonable position: the gentlest routine is to remove most of the water quickly, then let hair finish drying on its own. That avoids both prolonged wetness and prolonged heat.

• Fine hair that dries quickly on its own: air drying is straightforward and sensible.
• Thick or dense hair that stays wet for hours: rough drying on a cool setting to 80 percent, then air drying, is probably kinder than either extreme.
• High porosity or chemically treated hair: avoid long soaking periods, and use low heat rather than none.
• Curly or wavy hair: air dry or diffuse, and avoid disturbing it while it dries.

The worst options are clear enough: hair left soaking for hours, tied up wet, or blasted on maximum heat from dripping wet. Most sensible routines sit somewhere in the middle.