Knowledge: To bleach tshirt to do tie dye, the artist must put wear gloves to protect from the harsh chemical. On the other hand, to hair dye to purple, one must decolorize then color to desired color.

Conversation:
I'm sick of my purple hair, but I'm not sure if changing it would be too damaging to my hair.
There are several reasons people get their hair dyed, like covering gray, or as a fashion statement, or just to restore hair color that's been damaged. What's your reason?
Both fashion and because I'm getting some gray hair.
Ah, Okay. It turns out there's a trend of young people dying their hair gray, called Granny gray.
Sounds interesting, can I do it at home or do I need a salon?
You can do it at home or it can be done professionally.
Ah I see. Do you think I need to bleach it first?

Response: Yes, to dye the hair to purple, you must bleach the hair first.