I don't bother to designate pipes for several reasons. I don't smoke Lakeland aromatic blends, which are he worst ghosting offenders. I have a lot of pipes, so my rotation is large, so I don't get much flavor carryover for that reason. And most of all, I don't build cake, so there is less of a carrier for residual flavors. I scoop out the ash after each smoke, and after running a pipe cleaner though the airway, I use an abrasive paper towel to remove all the loose material in the chamber. I have never detected any residual flavors from aromatics, Latakia, Perique, or heavy strong burleys or dark fired. Also, this method retains the diameter of the chamber on a permanent basis. Cake building is a fine old tradition, and many enjoy it. But it's not for me.