From an anonymous commentor comes this question...
I read the following from your pdf on conditioners: The main conditioning agent in BTMS (behentrimonium methosulfate) is a cationic quaternary ammonium salt derived from rapeseed oil (the plant for canola oil).
My questions are: Any of the shampoos that have ammonium sulfates in them totally wreck my hair. I can use SLeS shampoo fine. But the ALS ones are just awful. This makes me wonder, would the ammonium salt in the BTMS be bad for my hair too? Or is it a totally different kind of ammonium?
Ammonium is ammonium - the molecule is the same (NH4). It's what is connected to that ammonium molecule that makes it a negatively charged ammonium lauryl sulfate (ALS) molecule or a positively charged BTMS molecule.
ALS is only slightly less irritating than SLS, so it is more likely to be the fact that what are called the alkyl sulfates are considered to be amongst the least mild surfactants in shampoos. (They're nice and cheap, which is why they show in commercial shampoos all the time.)
It is also possible that another ingredient in the shampoo is causing you problems. Perhaps there's an association between shampoos that use ALS and the use of silk, or the type of thickener they use (salt works with some surfactants, but others need different thickeners). There are tons of ingredients in a shampoo - it's hard to pick out just one that might be annoying your hair!
As for conditioners, most cationic quaternary compounds we use - including BTMS, cetrimonium chloride, cetrimonium bromide - contain ammonium as the positively charged molecule that makes a conditioner a conditioner. Most - if not all - of the cationic polymers like honeyquat, polyquat 10 and so on - contain an ammonium molecule. And many of the new hybrid silicones contain ammonium. So if you've used a commercial conditioner in your life, you've used something with the ammonium molecule.
I don't think I'm qualified to diagnose problems, but if I had to make a guess, I'd say the ammonium molecule isn't your culprit!