Skim through

What it does: emollient, conditioning

The science

Cetyl ester is primarily used to thicken emulsions while acting as an emollient for improved feel. It also prevents formulas from separating.

Benefits for your hair

Conditions hair

As it is water repellant, moisture loss is prevented and thus, it is a great conditioning agent. 

TLDR 

Cetyl ester is a great ingredient for conditioning and improves the application process.