I really wanna bleach my backpack like this http://img2.etsystatic.com/002/0/7123842/il_fullxfull.367910610_jmhn.jpg but instead of shorts it will be my backpack. I just don't know what to do. Like is there a special kind of bleach I need? How much should I get? When I'm bleaching it how long should I leave the backpack in the bleach? And is it even possible to do that to a backpack?