Some residue from ink is normal and that’s why we’ve made Dopesticks super affordable. Just like any product they will wear out from use. Sun and heat created additional wear after being left in the sun for over a month during testing, however the prototype still works. None of these conditions take away from the experience of the Dopestick but we want to give you all the intel from our testing. On the fly, you can rub ink off with sweat and your thumb if you’re in a pinch.