Two general forms of conditioners are currently in use: (1) hair rinses and (2) leave-in products, often referred to as ‘‘deep’’ conditioners. Both are applied to freshly shampooed hair. True to their name, the rinse product is rinsed off after a few minutes, whereas the leave-in product is left on the hair for up to 30 minutes, after which it is rinsed off. The purpose of the longer time is to allow the product to penetrate further (thus the name ‘‘deep’’) into the hair shaft thereby extending the conditioning effects.
The active ingredients in most conditioners are based on quaternary ammonium salts (cationic surfactants) such as steartrimonium chloride and, cetrimonium chloride, and the like. Because of their great affinity for hair, these compounds bind strongly to the cuticles, providing a low-friction surface, thus making the cuticles slick and less prone to abrasion. Other components present in the conditioning for- mulations, such as fatty amines, fatty alcohols, and amine oxides, supplement the action of cationic surfactants, adding primarily to the tactile benefits. The leave-in conditioners that are recommended for use on damaged hair frequently contain protein and lanolin derivatives.