<P> The four most common classifications are permanent, demi - permanent (sometimes called deposit only), semi-permanent, and temporary . </P> <P> Permanent hair color generally contains ammonia and must be mixed with a developer or oxidizing agent in order to permanently change hair color . Ammonia is used in permanent hair color to open the cuticle layer so that the developer and colorants together can penetrate into the cortex . The developer or oxidizing agent comes in various volumes . The higher the developer volume, the higher the "lift" will be of a person's natural hair pigment . Someone with dark hair wishing to achieve two or three shades lighter may need a higher developer whereas someone with lighter hair wishing to achieve darker hair will not one as high . Timing may vary with permanent hair coloring but is typically 30 minutes or 45 minutes for those wishing to achieve maximum color change . </P> <P> Demi - permanent hair color is hair color that contains an alkaline agent other than ammonia (e.g. ethanolamine, sodium carbonate) and, while always employed with a developer, the concentration of hydrogen peroxide in that developer may be lower than used with a permanent hair color . Since the alkaline agents employed in demi - permanent colors are less effective in removing the natural pigment of hair than ammonia these products provide no lightening of hair's color during dyeing . As the result, they cannot color hair to a lighter shade than it was before dyeing and are less damaging to hair than their permanent counterpart . </P> <P> Demi - permanents are much more effective at covering gray hair than semi-permanents, but less so than permanents . </P>

Who was the first to dye their hair