because its a creme peroxide, it doesn't seem to dry out very badly.
I left it for 2 hours at a time, in direct sunlight, on about a 22 degree day
I checked it after an hour, and reapplied the peroxide if I thought it was needed.
then, after 2 hours, I washed it all off, and reapplied the peroxide, and left it in the sun again.
did this 3 or 4 times total.