People whose scalps get dry are probably pple who have naturally dry skin. Adding Essential Fatty Acids to one's diet and drinking lots of water might help. Also avoiding harsh shampoos that are extra-drying wouldn't be a bad move. I know when I first stopped greasing my scalp, my scalp felt dry. It no longer does. My guess is, your sebaceous glands take a back seat coz you're supplying all the oil they could be supplying, so why should they bother. But when you stop greasing your scalp, you wake them up coz they can't afford to sleep on the job since no one's covering for them anymore. (But don't quote me. That's just how I see it.)
The oil from the gland isn't sufficient to oil our curly hair when it grows long the way it can be for straight hair. For lack of a better explanation. Imagine yourself sliding down a smooth pole, you'd slide all the way to the bottom without any problem right? But now picture yourself sliding down a pole that folds one way then the other, instead of pointing straight down. You'd probably slide only a short way down before you stopped at a bend. At which point you'd have to manually push yourself along to get past the horizontal part due to the bend so as to head on vertically down by gravity. Well, in the case of hair, you are the oil molecule, but unlike you, the oil molecule doesn't make an effort to push itself past the kink. Which is why those with curly hair cannot rely on their sebum to supply their entire strands the way those with straight hair can. The oil would stop at the first bend and call it a day.
There are some pple who put grease on their scalps but still have long hair. We probably know relatives who swear by Dax and have been greasing their scalp since back when, yet long hair has never eluded them. These are probably the same pple who can treat their hair carelessly and still not have to worry about length. However, most of us who apply stuff on the scalp do not use grease or mineral oil but rather, we use water based products or essential oils or natural oils (like coconut, jojoba, avocado...to name a few) all which are penetrating oils. They don't just sit on the scalp like grease would but their molecules are small enough for them to actual penetrate the skin or hair strand. They therefore do not clog the pores as grease might. (BTW jojoba is the closest thing to our natural sebum.) I know for me, I have had better success in my hair growth ever since I stopped applying grease on my scalp. So whether it's true or not, I'm more inclined to believe grease clogs pores. I also have clearer skin. Go figure.
Protein is a body-building compound. Eating protein can help with new growth and repair of cells inside the body. But hair that is outside the scalp that is "dead" cannot benefit from the protein you eat. However, this "dead" hair does become usually porous due to the cuticle being broken by wear/tear or due to chemical/heat use. The only way to fix those "cracks" is by applying protein to the hair itself. Think of plugging holes in the wall with plaster. If you don't believe protein adheres to hair, just try using some and then see how hard your hair gets. You could rinse and rinse till you're blue in the face but your hair will still be hard from the additional protein it now has. But that too gets worn off with time which is why repeated treatments are necessary.
The only way to avoid damaging your hair with hardwater is to buy a filter for your shower. In the meantime, please make sure to use an apple cider vinegar rinse in your wash. Some pple do it before applying conditioner; some at the very end. If your water is very hard, I'd say do it both times. ACV helps neutralize the alkalinity in hard water. Alternatively, if you can afford it, do what some pple here do: buy distilled water just for your hair. Those who have tried this swore it made a huge difference to their hair.
OK, I'm now off to read the link you provided. (Maybe I shoulda read it first. /images/graemlins/tongue.gif )
