Essential Oils are optional but can add great benefits to the spray.
Any carrier oil works.
2 tsp of Vitamin E oil can be added to the spray, if desired.
I have dark coloured hair and it works great on it. I haven't used it on light/blonde hair. Due to using hibiscus tea, this spray may add a light red colour to light hair, though it should wash out. If you are worried, use water instead of hibiscus tea.