Journal

Measurement, optics and hair.

What can actually be measured on a hair fibre, what the numbers mean, and how to test a routine the way you would test sleep.

  1. 13 Aug 2026 · 6 min

    How to measure hair health at home, without guessing

    Most advice asks you to eyeball your hair in a mirror. Here are the five properties of a hair fibre you can actually measure, and what each one tells you.

  2. 13 Aug 2026 · 5 min

    What makes hair shiny? The optics, in plain terms

    Shine is not a substance you add. It is a geometry problem on the surface of the fibre. What specular reflection is, why a closed cuticle produces it, and what silicone actually does.

  3. 13 Aug 2026 · 5 min

    Frizz is data: what stray fibres say about humidity and breakage

    Frizz gets treated as a styling annoyance. Counted per centimetre, it is an early-warning signal with two very different causes, one reversible and one not.

  4. 13 Aug 2026 · 5 min

    Hair thickness in microns: what fibre diameter actually tells you

    Human hair runs roughly from 40 to 120 microns in diameter. What that number means, why it changes slowly, and why it is the baseline of any serious measurement.

  5. 13 Aug 2026 · 4 min

    How the FIBR score works: five measurements, one number

    A single score out of 100 is only trustworthy if you can see how it is built. The exact weights, why Frizz is inverted, and why the score compares you to yourself.

  6. 13 Aug 2026 · 6 min

    How to test a hair routine in 30 days, the way you would test sleep

    Wearable users learned to test one change at a time and read the trend, not the day. The same protocol applies to hair. A concrete 30-day plan, with or without a device.