pliable. The scalp produces a natural oil called sebum. EFAs are the closest thing to natural sebum (sebum contains EFAs). Preservatives that protect the product from spoilage by microorganisms during the product shelf life. Reconstructors, usually containing hydrolyzed protein. Their role is supposedly to penetrate the hair and strengthen its structure through polymer crosslinking. Sequestrants, for better function in hard water. Sunscreen, for protection against protein degradation and color loss. Currently Benzophenone-4 and Ethylhexyl Methoxycinnamate are the two sunscreens most commonly used in hair products. Cinnamidopyltrimonium Chloride and a few others are used to a much lesser degree. The common sunscreens used on skin are rarely used for hair products due to their texture and weight effects. Surfactants – approximately 97% of hair consists of a protein called keratin. The surface of keratin contains negatively charged amino acids. Hair conditioners therefore usually contain cationic surfactants, which don't wash out completely, because their hydrophilic ends strongly bind to keratin. The hydrophobic ends of the surfactant molecules then act as the new hair surface. Examples are Behentrimonium Chloride and Cetrimonium Chloride Thermal protectors, usually heat-absorbing polymers, shielding the hair against excessive heat, caused by, e.g., blow-drying, curling irons or hot rollers. pH Conditioners are frequently acidic, as low pH protonates the keratin's amino acids. The hydrogen ions give the hair a positive charge and create more hydrogen bonds among the keratin scales, giving the hair a more compact structure. Organic acids such as citric acid are usually used to maintain acidity. See also Anointing Brilliantine Brylcreem Pomade Shampoo References External links How Hair Conditioner Works at h2g2 How to Apply Hair Conditioner at wikiHow Hair care products