Re: How to measure tensile strength of hair with certain moisture content?

The question: "How to measure tensile strength of hair with certain moisture content? I am currently investigating the effect of moisture on tensile strength of hair. However, my school lab's equipments are limited. Thus, I am wondering whether there is a simple yet accurate way to measure tensile strength of hair or not. And also how to control the moisture content of the hair."

There are two practical ways to control humidity in a closed container: with a(n expensive) humidity cabinet, or by using saturated salt solutions. Using Google, for instance, search on

controlled humidity salts

Inside a container of controlled humidity, allow each hair to reach moisture equilibrium. The amount of time required will vary depending on hair type, but shouldn't take more than 15 minutes at the most. Hang a weight holder to the end of the hair, and then add weights until the hair breaks.

You will need to measure a minimum of three hairs of each type at each humidity. That means a lot of testing, but it is necessary so that you can calculate an estimate of the standard deviation of your method.

John Link, MadSci Physicist