Q: Nedra (lovely name!) has been cowashing but really needed to clean her hair, so she modified her shampoo by adding honey and olive oil. The effect she says is that her hair felt moisturized. She asks, 'So is it possible to use shampoo in this way without all of the drying effects?'
A: The reason why shampoo leaves hair feeling dry is because it is supposed to. It is designed to dissolve oil. I will repeat that. Shampoo is designed to DISSOLVE oil.
Why dissolve oil you ask? The oil on hair (whether self-made or applied) attracts dust and dirt. Do you ever find that your hair collects lint over time? If you have oily hair or regularly add oil to your hair, the reason why the lint is there is because, it is attached to the oil.
There are two known safe ways to dissolve oils, one is to dissolve it in another oil, but this would not clean hair. The second is to use a surfactant which can force the oil into water.
Shampoo is designed to dissolve oil into water. You can learn more by looking at the surfactant and micelle posts - here and here.
Adding oil to a shampoo probably reduces its cleaning power because the surfactant will start binding to that oil instead of the one on your hair. However if the mixed shampoo is still able to clean your hair to a standard that you like, then there is no harm. Honey is probably fine since it is mostly sugar and that should not interfere too much with the surfactants in shampoo (honey safety is a wild theory I should add)
Q: Second question from Nedra, she added a small amount of baking soda to her conditioner and said that she did not notice anything except shedding which could be attributed to the fact that she had not removed shed hairs for several days. She asks, 'Is the baking soda really that dangerous?'
A: Umm...yeah (ducks!). I did do a little experiment on baking soda in conditioner and it does dramatically change the pH from a more or less neutral state to quite alkaline. The amount of baking soda required for this recipe was massive!
I personally would not recommend mixing it in conditioner. The high pH is known to affect the cuticle, causing lifting. I do know there are some ladies who do swear by its cleansing power and some even say it can relax hair. My own little experiment did not demonstrate this effect but my hair is pretty resistant to normal relaxers anyway. I would think with its high pH it is probably a good cleanser but it may come at a price.