you know whats funny.. i've been getting my hair done since i was a sophomore in high school (8 years ago!) and i now have my cosmetology license and i still wont touch my own hair unless i'm doing it all one color or toning it. i have like black hair practically and will never do it myself or let someone else touch it with bleach other than my stylist... i learned the hard way
i dont do highlights with a cap i always do foils or balayage but for you ladies that do the cap frosting/higlighting whatever it is from the box at home... make sure the bleach doesnt touch the top of the cap and you shouldnt have any problems. bleach expands when it processes so thats why it can get under the cap and then you get spots! & also if you have black/dark brown hair.. the blonde highlighting kits that you get from the store will never get you blonde just orange. hth!