Password For E-Guide

Now don't cheat yourself here....the password to the e-guide is the answer to this Mensa riddle. I use Mensa riddles to keep my mind sharp, and to always remind me to think outside the box..so have fun with it!




WHAT IS BLACK WHEN YOU BUY IT, RED WHEN YOU USE IT AND GREY WHEN YOU THROW IT AWAY?

(One word and it's all lower case letters)