What does a filler do to your hair?

Question

Today i went to go see a hair pro to ask them what i should do to my hair to get it dark brown from light brown, and she said you need to put a filler or correction in your hair to take out all the dye that you ever put in your hair or something. Then you keep that color or you dye it again or something ... ya i dont know much about it or what it does to your hair if it damages it at all.

Dont answer if you dont know what a filler is and your just saying that you dont know what it is.

Answer 1

okay...you are going from a light brown to a dark brown (correct?).  i am assuming the light brown hair is artificial haircolor.

so assuming your hair was lightened from its natural color to obtain the light brown, you stripped pigment out of hair to achieve that light brown.

now when you want to go dark again you may need to use a filler to replace the natural pigment lifted previously.

the filler (which is usually a haircolor with what ever primary base or bases you are trying to replace), is used to so that your dark brown will be the closest possible match to the desired shade of dark brown you want.  fillers also help reduce fading, and more importantly help against you turning a completely undesireable color (gun metal grey, green, etc.)

i hope that i made sense to you...its all color theory.