I just went and checked the flue today and I had my usual buildup. Ive heard that some creosote is more dangerous than others and Im curious if I have to worry or if perhaps Im doing something wrong. I do plan on cleaning the flue this weekend and its been about 1 month-1.5 months since the last cleaning. I try to keep flue temperatures "In the white" on my thermometer, approx 300-450. Im burning mixed hardwood, mostly maple. Some cut this year, and some CSS for 1yr. In my flue, there is two distinct types of creosote and they happen in two different types of stove pipe. In the upper Selkirk style pipe, I get this light brown, fluffy buildup that's easy to clean. Im not too worried about that, should I be? The lower, single wall pipe is where I get concerned. The buildup is hard, shiny and black. Tiere is also considerable flaking where the creosote comes off in large (1"x1") sheets. The cleanout cap is regularly filled to the top edge with these flakes when it's cleaning time. Flaking: FLakes in cleanout cap after dumping out the loose stuff: Hard, black buildup (in foreground) in single wall T leading into selkirk. Looking down into the 90* that leads to the stove. Notice flaking. Also hard black creosote Looking into T. 90* to stove is on bottom. Top of T going to selkirk is on top. Area is full of shiny hard creosote, although the picture does not show the shine very well. When I clean the stove with my Sooteater, all the brown fluffy stuff and any loose flakes are easily removed, however I cant get the hard black shiny stuff off. Im concerned that by leaving the shiny stuff behind, it's promoting more and more growth of it. Even a hand held wire brush cant cut through it. Is there a way to remove the hard stuff?How about that powder you sprinkle in the fire? Is there any reason to be concerned over the hard stuff being left behind after cleaning other than the fact that is seems to be getting thicker and promoting more of the same?