Been burning the 30nc for a month now. I finally picked up some brush poles for the nylon brush I bought with the pipe. I have 26ft of outside pipe and after cleaning , I got about 2 table spoons of cleanings. Not sure if it is all creosote or just other build up. Does more than just creosote make up what you get when you clean?Anyway it all looked like the size of sugar granuals just black,so I am pretty happy with that. Been burning a mix ox ash and box elder mostly.