Heat styling without frying your hair

See how it works

Do this

1. 1Dry hair completely first. Never iron damp hair.
2. 2Start at a low temperature. Raise it only if the style will not hold.
3. 3One or two passes per section. Do not keep going over it.
4. 4Apply heat protectant, let it dry fully, then use the tool.
5. 5Hair already bleached or relaxed? Use less heat or skip it.
6. 6Give your hair heat-free days. Replace any dryer that overheats.

The numbers behind it

• 237 C

  Hair protein (keratin) loses its structure at about this temperature. Gases appear from 200 C. Lab test, 3 hair bundles.

  Lima 2019 ↗

• 190-220 C

  Between these iron temperatures the number of tiny holes inside the hair rose quickly, and with each extra pass.

  Gamez-Garcia 2011 ↗

• Wet is worse

  Ironing wet hair caused considerably more structural damage than ironing dry hair, with the same chemical damage.

  Christian 2011 ↗

• Helps a bit

  Repeated heat-protection spray reduced one chemical marker of heat damage (loss of an amino acid, tryptophan). It did not stop the structural damage.

  Christian 2011 ↗

For your hair

• Fine hair

  Thin strands heat through fast. Keep the temperature lowest.

• Thick or coarse hair

  May need a little more heat to style, but damage still adds up pass by pass.

• Curly and coily hair

  Heat can loosen curls. Protect the ends and keep straightening occasional.

• Bleached or relaxed hair

  Treat as already damaged. Heat on top compounds it.

Myths to ignore

• Myth A heat protectant makes high heat safe.

  Truth In a lab test, protectant sprays cut one chemical marker of damage, but structural damage still happened. Lower temperature matters more than the spray.

  Christian 2011 ↗

• Myth Steam or a water-based spray lets you iron damp hair.

  Truth Water on hair plus a hot iron gave considerably more structural damage than the same iron on dry hair. Rapid evaporation is the likely cause.

  Christian 2011 ↗

• Myth Bubble hair only happens to already damaged hair.

  Truth When researchers heated hair from 16 volunteers, every one of them developed bubbles at high enough heat. It is a dose of heat, not a hair type.

  Detwiler 1994 ↗

Made for this

• Leave-in Heat Shield Leave-in mist to use before blow-drying or hot tools
• Repair Mask Weekly reinforcement for bleached, heat-styled or brittle hair

Go deeper

• Heat styling toolsFlat irons, curling tools and hot combs damage hair more with higher temperature, repetition and wet hair; dermatologists advise using them about once a week or less.
• Heat damage and heat protectantsHeat on wet hair is the clearest harm, and there is little independent evidence that retail heat-protectant sprays work.
• Hair damage: what it is and where it comes fromDamage is cumulative and cannot be biologically healed, and chemical treatments, heat, sun, water and grooming each add to it.
• Hair dryingAir drying is not clearly safer than moderate-heat blow-drying; high heat, close range and heat on wet hair are the real problems.