I have had this problem in the salon before with the Halloween sprays. It really depends on the condition and porosity of your hair. I had one girl who put in the red and it stained her hi-lights pink. You could always do a test strand and see if it washes out after, before you spray your whole head. I am not trying to scare you, just want to warn you that just because its temporary doesn't mean it wont stain your hair where the hi-lights are.