after languishing with flu for over a week I am booked to go to a new salon to have my hair highlighted. They have done a patch test on me today, but do I leave the colour on for the next 24 hours or can I wipe it off (but won't wash it)? There is quite a hefty smear of colour behind my ear. It has been on for 7 hours now. (And no reaction as yet thank goodness).