I have a 18' long 6" DIA. Flexible SS liner for my jotul#3 wood stove. My first cleaning was a few weeks back. When I removed the cap I found a 1/16" coating on most of the liner,and a 1/8" coating on a 2 foot section witch was at the mid way point of the liner. The coating was very dry and looked like millions of pencil leads. The stove and new liner had about 50 12 hour long fires on them at the time of the cleaning. I was burning several types of wood,,everything from pine to oak,,semi-green to very dry,,whatever I could get. How thick do you let the dry build-up get?