I consider SistaSlick the expert on all thngs hair, and her article will really give you the information you need.
Think of a strand of hair like a fish scale. The scales are supposed to be flat and closed protecting the inside. If you have that picture in your mind, apply it to your hair. The cuticle of your hair should also be flat and closed protecting the inside (cortex). Water, hair products, etc. (high pH) can lift the cuticle, exposing the cortex. This exposure can cause damage. The exposure also dries out the cortex, so you want the cuticles flat.
The purpose of porosity control and other acidic products is to make the cuticles be flat against each other which keeps in moisture, makes hair shiny, etc.
If someone says you have a porosity problem - like your dry hair problems - it means that the cuticles are lifted, moisture evaporates quickly, so it seems that the products you are using to moisturize your hair are not working. They are, in fact, working, but the state of the strands - lifted cuticles - allows for faster evaoporation of the moisture you're putting inside/on the hair strands. This means drier, weaker strands of hair.
Try Porosity Control, acv rinses, or other products that specifically indicate a low pH closes the cuticle like the fish scale - and this is what you want to do with your hair products.
For your homework, outline the article and the fish scale analogy.
Ok, ladies. Maybe I'm having a blonde moment...but in my defense I did try by researching and I'm still lost. 
Can my kind and patient LHCF family members, in simple terms, please explain porosity (high & low) and what to do about it? This stems from a thread that I started about "Does Your hair laugh at your Moisture Efforts" and someone suggested that I may have porosity issues and that there is even a product called Porosity Control or something. I'm just lost and frustrated because it sound like that's what my problem is and I never knew all this time. So, what is it and how the heck do I remedy it? How do you use the prodcuts? Does it repair instantly or does it take a while?
Thank you Newflowers....and to think, all it took was a fish!!!
.....I saw a million different ways to use it. THANKS AGAIN!!!!
