Question: I am burning a Blaze King wood stove that exhausts through an eight inch round connector into an eight inch square exterior masonry chimney. The thimble through the wall is a six inch round thimble so I had to use a reducer at this point. Every three to four weeks this winter when I take the connector pipe off and clean it out , I find a paper thin layer of creosote covering quite a bit of the opening of the thimble inside the chimney. In some case's this is covering 2/3 or more of the opening. It breaks away easily but obviously this is having a negative effect on my draft as it is accumulating. Last year using a different style stove I never experienced this problem. I notice no dramatic difference in the build up in the chimney itself from this year too last year, only that this thin film is occurring constantly and frequently. The stove that I used last year had a six inch connector all of the way from stove to chimney. Could the reducer going into the chimney be causing this? Answer: You might be onto something. Although you really should not reduce at all, it may be best to reduce right at the stove if you are going to do this. The other and better solution would be to install a 7 or 8" inch crock. The creosote you describe is probably "already burnt" stuff which is falling off the pipe and chimney and collecting in the lowest point.