What happens when you bleach your hair when it's brown?

When you bleach your hair, it gets stripped of the pigment which it naturally has. Bleach penetrates the body of the hair by opening up your hair cuticles, then lifts and destroys the pigment in your hair gradually, during the time bleach is left on the hair, affecting outer layers of the hair first, going deeper to the core of the hair as time passes. If your hair is brown, it will go through three stages - first, it will turn orange, then yellow, then very pale yellow or white. If your hair was black, it would go through four stages, as the first stage would be turning to red, and the other three would follow as already described. Because of the mentioned penetration of the hair and weakening of it by removing one of its components (pigment), hair becomes fragile and brittle, thus post bleaching hair care must be applied.