One reason is I have made soap products in the past, bar shampoo being one of them (in the form of 'cookies' and 'muffins'), so am aware of the process, the retention of glycerin in 'homemade' soap, the feedback from friends about the benefits of products without anything harmful or irritating, the satisfaction of DIY.
Another reason is the increasing awareness (scientific scrutiny/ media attention) that what we put on our bodies is as important as what we put in it. This leads to reading labels more intently and boy, the stuff they put in commercial shampoos is alarming. Which led me to scratch my head after shampooing with a regular shampoo, touch fingernail to tongue, be able to 'taste' the shampoo. I re-rinsed thoroughly. Taste tested again with same result. Talk about clingability! Do I really want stuff sticking to my scalp that has ingredients I can't pronounce. Beer shampoo came to mind as a soothing choice....aren't hops supposed to be good for us.
Then I came across a recipe for shampoo in Grandma's Amazing Household Hints, a little book I picked up at a thrift store - a church thrift store, which likely gave it extra credence. The ingredients are: 1 oz olive oil, 1 egg, 1 tbsp lemon juice, 1/2 tsp apple cider vinegar. I happened to have all the components in the house, my hair needed washing - voila.
Well - it was an interesting experience. There was no lather to speak of; I used two applications and rinsed well in between; drying was done by brushing over the hot air vent (I admit I had some fear of curdling the egg if I used the electric dryer); I am still assessing the result, a day later.
However - main reaction - it feels very good; hair is soft and silky. However - main concern - my hair looks oily and I like it to look fluffy.
It got me thinking about making another batch of shampoo 'muffins' and 'cookies'.