Hair Glossary

Hair thickness can be measured by using a special micrometer screw gauge or by means of a special attachment to a microsope. A hair is usually the same thickness all along its length and has an average thickness of 0-05 millimeters. When soaked in water, a hair will increase in thickness by a greater proportion than it increases in length, as water entering the air spaces between the fibers of the cortex causes the hair to swell.