This post contains 2 links for testing hair thickness and porosity, an elasticity test follows.
To calculate the mean thickness of your individual strands, I have a test through this link which requires good eyesight and a steady hand.
©Science-y Hair Blog 2013
If you'd like to estimate your hair's porosity, this post may help.
To determine elasticity, here is a simple test. It is based on these averages:
1) A dry hair can stretch 20-30% of its own length before it breaks.
2) A wet hair can stretch up to 50% of its own length before it breaks.
If your hair is 6 inches (15 cm) long, if it has very good elasticity, it should stretch to 6.2-6.8 inches (~16 to 17 cm) when dry and up to 9 inches (~22 cm) when wet.
So grab several shed hairs, a ruler, a cup of water and try it out!
If your hairs are slippery, you need something for grip - latex or nitrile gloves or a pair of tweezers for one end will give you enough grip. If your hair slips even a little, the measurements will be off.
1) Measure the length of your dry hair pulled straight, but not stretched.
2) Hold your hair so it lines up with the end of the ruler, press that end down on a hard surface, Grasp the other end (be sure to note how much length is lost due to your grip) and pull steadily and gently until the hair breaks. Write down the measurement as "dry."
3) Repeat with a few more dry hairs.
4) Now for the wet-hair test. First soak your hair in water (preferably distilled or non-chlorinated water) for 2 minutes. Blot each hair to remove water before stretching. Then stretch and measure as before. Record these as "wet" measurements.
©Science-y Hair Blog 2013
Do the math. The number of inches or centimeters your hair stretched beyond it's original length (minus your grip) is the number to work with.
-Number of inches your hair stretched divided by original length x 100 = the percent of the original length your hair stretched.
- If your 6-inch long hair stretched to 8 inches when wet: (2/6) x 100 = 33%
If your hairs vary a lot in thickness, color, or texture, be sure to test those different hairs.
If your hair comes up a little short, say stretching 39 or 45% in the wet-test, that's good too. Those figures are not absolutes.
But if your hair is consistently breaking well below average, it is dehydrated and/or has a lot of vulnerable areas. Oils and conditioners can help prevent dehydration and add pliability. Proteins and amino acids can hydrate and/or form water-holding films to keep hair pliable and elastic. The smaller the protein (keratin, silk, amino acids) the more agreeable it is to more hair types.