When it comes to your hair's texture, whether it's curly, straight, frizzy or somewhere in between, whether or not it absorbs water and other humectants may determine how easy it is to style and what kind of products you should use on your tresses. Many people with chemical treatments, such as color and relaxer, have high porosity, which means the cuticle of the hair is able to absorb more moisture - because it's damaged. The cuticle is the outermost layer of a hair strand and is comprised of shingle-like layers. It protects the inner structure of the hair and, when damaged, can make hair appear dull and lifeless. When the cuticle is able to resist moisture and other elements, such as the sun, it's better able to do its job of protecting hair color and shine. Test your own hair's porosity by pulling a few strands out of your brush and let them sit in a bowl of water or a partially filled sink for a few minutes. If you notice they sink after a minute or two, then your hair has high porosity. If they stay floating, then you have low porosity. Hair with low porosity tends to frizz in humid weather because it absorbs more moisture from the air, so you'll need to take measures to help seal out water.