If you really want coppery highlights, then this might not be the highlighting kit for you. I too, have medium brown hair color and by using this particular kit I can control, to some degree, how blond my highlights will turn out. In other words, if I keep the solution on for 20 minutes (at least), I will usually end up with nice light blond highlights. But if I keep the solution on for more than 20 minutes well I can easily end up with bright, true blond highlights. The only disadvantage to this kit is that once you start pulling the hair through the holes on the cap, some strands can be heavier and some thinner, so you really can't guarantee the end result. But for coppery highlights I would recommend you try this kit once, and simply keep the product on for less than 15 minutes. Depending, again, on how thick your strands are, you should end up with either very subtle soft blondish highlights or a coppery effect. But remember even one minute longer and your hair will go blonder. Good luck!
not all highlighting/bleaching kits are the same. it all depends on how long you leave the bleach in for the longer the time the lighter the blonde, but never leave it longer then 30 mins, why is because you will have a heck of a time getting the bleach out because it hardens, i bleached my hair once and i didnt know the rule on how long to keep in for i kept one part in for over 45 mins and the other side 30 mins. i started on side earlier, it was not even when i came out, one side was lighter then the other, and high school kids are mean, XD but anyways, dont leave in longer then 30 mins no matter if your hair is dark it will turn white/platinum in that time. if you dont want blonde hair but you do want blonde streaks use the cap thing they have in the box [some boxes dont have them and dont leave in for long time maybe 15 mins at longest 20.