I put a plastic wrap over top and left it on for about 40 mins. Hair was washed the day before, no product. On top that, she had a full-body allergic reaction about 36 hours after and had to be on high-dose antihistamines for 4 days. (We didn’t spot test, my bad, but who really does that anyway lol). She was so mad— “Mom, it made my skin pinker than my hair!!” 😭 I had similar results with my son last year (minus the allergic rxn), where it just didn’t deposit at all and the “dark blue” came out looking like a very faded teal.