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It's time to examine the float test for hair porosity more fully. I began looking into how the float test could give you an inaccurate result in the previous post . Elsewhere on this blog I have mentioned that this test is not very accurate. This post will show you why. To make the test more accurate, see the tips at the end of the post © Science-y Hair Blog 2 The idea behind the float test follows this line of thinking: If hair is porous, it takes on more water than if it is not porous. Therefore, porous hair might sink because it takes on water and becomes heavy. That is - the weight of the water the hair is absorbing overwhelms the power of surface tension (between water molecules) that keeps the hair suspended on top of the water. And in a sense this is not wrong but it is incomplete. But there are too many other variables in play to make this an accurate assessment of how porous your hair is by simply grabbing some hair and dropping it in a glass. Your experiment needs ...

Managing Elasticity and Porosity: "How To" and a little of the science behind it. Elasticity is a hair character or property that overlaps with porosity. Human hair is elastic - it stretches a little. It stretches a bit more when wet than when dry when it is well cared for. If we over-stretch our hair, it will be damaged. But hair that stretches rather than breaks is a good thing because it's still there to protect our heads. ©Science-y Hair Blog 2014 When hair is dehydrated, it loses it's elasticity, its "stretch." Think of leather or rubber or wood left in the sun and wind for a long time. It becomes dehydrated, loses it's flexibility and becomes brittle. When hair is porous, it loses water more rapidly than is good for it. Hair can be porous because it has been out under the sun a lot, as a result of frequent washing or wetting or lots of brushing, from hair dye or highlights or swimming pools or chemical relaxers or permanent waves or high heat styli...

First off -  think of your hair not as a fiber like yarn because hair is more complex. Think of the inside of your hair like string cheese - protein which is flexible and retains water - it will swell when wetted. Then think of the cuticle as though you glued several layers of tiny, overlapping shingles to the outside of the cheese. You've used proteins and amino acids and lipids (fats) to glue all this together. It's flexible - but it's also prone to damage because proteins and fats do break down. Your hair's porosity is probably not the same at the roots as at the ends, the ends are usually more porous. "Pores" are openings in the cuticle layer(s) - whether they are chipped or torn cuticle scales (imagine torn or ripped-off shingles), or cracked, shrunken and fused, or simply not glued down very well. Any of these situations leads to a less-protected hair cortex - which means your interior of string cheese will dry out more quickly. ©Science-y Hair Blog 2013...