View Single Post
Old 11-30-2005, 07:08 PM
brainygirl's Avatar
brainygirl brainygirl is offline
Senior Mentor (Leader, Team D)
Join Date: Oct 2005
Location: U.S.A, Rhode Island
Posts: 78
Rep Power: 19
brainygirl is a brilliant scientist admired by others
Send a message via Yahoo to brainygirl
Post This might help!!!

Measuring hair fiber strength under different conditions.

Hair takes on different properties depending on humidity and chemicals it has been exposed to. You might try looking at the strength of hair that has been treated in different ways. The basic system involves tying a strand or maybe several strands of hair to a stand. At the other end tie a hook that you can hang weights on. Put a ruler by the side of the hair fiber and add the weight gradually. As you gradually add the weight, you should see the hair fiber stretch before it breaks. By measuring the length of hair at different weights and plotting the results on a graph you should get a nice curve. By recording the amount of weight it takes to break the hair you can work out the hair strength.

To make things more interesting, take a few hair strands from someone who does not chemically treat their hair and some strands from someone who perms, bleaches, or permanently colors their hair. Ideally get and use the treated hair within 24 hours of treatment (try the local hair salon for volunteers). Compare the "stretchability" of treated and untreated hair and the overall strength. Treated hair should be weaker although if there is enough time between treatment and testing the hair will recover its strength.

Additionally, look at the properties of wet and dry hair. Hair immersed in water for an hour will swell by up to 20%. Ideally, heat the water to 50 degrees centigrade get maximum absorption into the hair. Test the strength of this wet hair versus "dry" hair (not strictly dry as all hair takes in water to some degree depending on air humidity). The wet hair should weaker by up to 30%. Hair strength in normal air humidity is somewhere between 1,000,000gm/cm square to 1,250,000gm/cm square - as strong as copper wire of similar diameter.

Good Luck!
"Your faith in yourself is all you will ever have. Don't let anyone take it away from you ever."
Reply With Quote