Okay we are gonna start with the parts of the hair. There are 3 parts of a human hair. the innermost part is called the Medulla. The middle layer is called the Cortex. The Cortex contains all the stuff like hair color pigments known as Melanin. The outer layer is the Cuticle which is made up of a bunch of tiny fish like scales.

Now we are gonna discuss the word Porosity. Porosity is the ability of hair to absorb liquids. The term porosity refers to how many holes or Pores the hair has. In other words how Porous is the hair? In order to explain porosity I came up with a simple way. Lets say you have 3 blocks of wood. One block of wood is smooth and does not have any holes. The second block has 5 holes drilled into it about halfway. The third block has about 20 holes in it. The block with no holes is the least Porous. The block with 20 holes is very porous. Now lets say we have 3 separate cups filled with 1 cup of water each. If we pour water on the smooth block it will soak into the wood but it will take forever. If we pour the water on the 5 holed block it will soak in fairly fast. If we pour the water on the 20 holed block it will soak in super fast. Now Your hair is like these blocks of wood. One hair strand might have all three degrees of porosity ranging from least porous at the scalp and most porous at the ends. The reason is because your ends have been exposed to the elements longer.

Now about those elements, acids and alkalies. The pH scale is a scale that tells whether something is acid or alkaline. It ranges from 0 to 14. 0 - 6.9 are called acids, 7 is neutral, and 7.1 - 14 are alkalies. When you look at a pH scale the closer to 0 or 14 you get the more damaging it is to your hair. The closer you are to 7 the better it is even though it may still damage your hair.

Acids close the cuticle layer (the scales). Alkalies open the cuticle and attack the cortex. Bleach, Ammonia, Relaxer are all alkalies. Acids can be things like vinegar or lemon juice or anything that says acid. Battery Acid aka Hydroflouric is 0 and Stomach Acid aka Hydrochloric is 1