Q1: Why is behentrimonium good?
It is probably one of the best conditioning agents for softness. It acts by depositing on hair and helps to smooth down the cuticle (because of that positive charge). It has a fairly long tail (go back and see its structure here). This long tail causes behentrimonium to be attracted to hair more so than short tail surfactants (Journal of the Society of Cosmetic Chemists, pg 85-94, 1994)
Q2: How to use behentrimonium?
Behentrimonium is enhanced in combination with cetyl alcohol (Journal of the Society of Cosmetic Chemists, pg 251-263, 1989)
Q3: How not to use behentrimonium?
Similar conditioning agents to behentrimonium have been seen to be less effective when pH was low. A low pH means an acidic rinse for example acidic shampoos or ACV rinses (Click here for more on pH). Generally most shampoos are of neutral pH which is ideal for behentrimonium. There is however a school of thought that shampoos should be slightly acidic to match the fact that hair is slightly acidic..........so just bear in mind if you are using these type of acid products, you may not get the best result from behentrimonium
Q4: Any other notes?
Behentrimonium is a surfactant and therefore it can be used to wash hair. It is however not very effective at this because of its very long tail. Short surfactants such as SLS are much better at lifting oils - see this post.
Are you in love with behentrimonium? I am with the herbal essences intensive mask (in a jar not a tall bottle!). I keep seeing these pictures of the tall bottle and people saying it has behentrimonium, which actually it doesn't, atleast not the bottle sold in UK.
What is your favourite conditioner with behentrimonium?