Hair Testing | TRI Princeton | Hair and Skin Testing

Single-Fiber Thickness and Swelling

Laser Scanning Microscopy

The laser micrometer in action. The red laser light is just visible on the center of the fiber. In the tests the fibers are rotated to get an average diameter and a measure of ellipticity. Hairs are usually sampled in several points to get a representative reading.

Single-Fiber Hair Thickness and Swelling

Laser Scanning Microscopy

If you want to show that your product is increasing hair thickness, or volume, it is useful to perform hair diameter measurements. Additionally, since hair swells differently in water after various damaging treatments, hair swelling tests are also useful for measuring hair damage prevention and repair.

Hair diameter measurements involve shining a laser onto the fiber. A detector behind the fiber measures the size of the shadow created by the laser light and uses this to calculate the hair diameter. Hair diameter is thus measured without any contact with the instrument. The instrument can also measure hair ellipticity.