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Hair science, explained simply.

Plain answers to the questions most haircare advice gets wrong. Each page states its answer up front, explains the mechanism behind it, and names the research it rests on. Where the evidence is thin or the study population was narrow, the page says so.

• 01
  How often should you wash your hair? There is no universal number. Scalp oil refills at the same speed for everyone, but not the same amount, so the schedule has to match your scalp. Read the breakdown →
• 02
  Are sulfates bad for your hair? Not inherently. In one lab test a sulfate was the mildest of four cleansers. The molecule and the amount decide it, not one word on the label. Read the breakdown →
• 03
  Do silicones damage hair? No. They lay a film that cuts friction and adds shine. The real trade off is buildup and what it takes to remove it. Read the breakdown →
• 04
  Is natural haircare actually better? No. Where an ingredient comes from does not predict how well it performs on hair. Source is not a quality signal. Read the breakdown →
• 05
  Why shampoo pH matters more than the label pH sets the charge on the fiber surface, which sets friction. In 123 shampoos measured, pH ranged from 3.5 to 9.0. Read the breakdown →
• 06
  Leave-in or gel: what curly hair actually needs For most curly hair, start with a gel. A leave-in is optional, and what it does depends on what is in it, not on the label. Read the breakdown →
• 07
  Is hair thickness genetic? Largely. Genes accounted for 86% of the variance in fiber diameter in men and 77% in women. No product grows thicker hair. Read the breakdown →
• 08
  What your hair signals before you speak Five studies measured what people read from hair. What moved the results was condition, and for men, hair alone shifted how competent they looked. Read the breakdown →