Henna coats each hair shaft with a natural, semi-permanent protein called hennatannic acid. Heat causes the hennatannic acid to cling to the proteins found in the hair (or nails and skin, if desired). Because henna coats and seals the hair shaft, it helps protect the hair from damaging effects of sun, salt, chlorine, wind and pollution in the environment. It can help miminize split ends and acts as hair insurance if you spend a lot of time in the sun, surf or wind. In addition to protecting the hair shaft, henna will tighten the hair cuticle and create a more solid surface which reflects light; the result is gleaming, lustrous hair. Rather than producing dramatic color changes, henna enhances and deepens existing color. The darker your natural color, the less drastic the change will be inyour natural color. Because the color from henna is transparent or seethrough, henna cannot lighten dark hair; it will, however, add highlights to dark hair and can darken the color of lighter hair.