last pipe, i've been stuck on peterson, i thought something was strange with the coating in the bowl. but didn't pay attention since the pipe smoked great. got a new pipe and the coating was rather different from flat black coating i was used to seeing. now it's shiny thick black coating like someone poured black tar in it. while smoking, the draw was restricted. ran a cleaning and kept on smoking. then, i haven't reached bottom 1/4 bowl yet and it keep going out. emptied the bowl and noticed the coating was all at the botton mixed with tobacco bits and hardened. it wasn't all that hard to remove, but i'm wondering what's with this coating?