Final answer:
The hair has to be pre-lightened first.
Step-by-step explanation:
If the client asks for a dramatically lighter color (more than four levels), the hair has to be pre-lightened first.
Pre-lightening involves using a bleach or lightening product to remove the existing color from the hair. This process allows the hair to be lightened to the desired level before applying the new color.
For example, if the client has dark brown hair and wants to go to a light blonde shade, pre-lightening would be necessary to lift the dark pigment and create a blank canvas for the lighter color to be applied. Without pre-lightening, the darker color would interfere with achieving the desired lighter result.