I am by no means an expert...I saw a video of an expert(dont remember where) and he mentioned stripping the black skin then cleaning w a solution/cleaner w emphasis on NOT getting any cleaner inside the carto. Then punching or slotting (your choice) and using in a tank. I believe it was pbsaudro. Sorry for destroying his name. Thats close but definetly not right.
I took a small knife and kind of etched/scratched a couple of boge cartos for the purpose of marking diff flavors and it did come off fairly easy. Obviously, you want bare, clean steel inside the tank
Hope that helps good luck