Burning wood at low temperatures causes incomplete combustion of the oils in the wood, which are off-gassed as volatiles in the smoke. As the smoke rises through the chimney flue it cools, causing water, soot, and volatile compounds to condense on the interior surfaces. The resulting residue that sticks to the inner walls of the chimney is referred to as “creosote”. Creosote is black or brown in appearance. It can be crusty and flaky…tar-like, drippy and sticky…or shiny and hardened. Often, all forms will occur in one chimney system. Whatever form it takes, creosote is highly combustible. If it builds up in sufficient quantities and ignites inside the chimney flue, the result will be a chimney fire.The possibility of a chimney fire turning into a house fire is another serious risk. There are two ways that a chimney fire can ignite your home. A small crack in the flue can open up, allowing fire sparks to enter the cracks and set the house on fire. Or chimney fires can produce extreme temperatures hot enough to create a flash point that can start fires just from the heat alone. In order to properly maintain chimneys and heaters that burn wood or carbon based fuels, the creosote buildup must be removed.We highly recommend using a quality nylon / plastic bristle poly brush to clean all types of stainless chimney liners. For your convenience, here is a link to the chimney brushes we offer.