Creosote is a toxic, potentially deadly byproduct that results when gases released from the burning of wood coalesce and settle within a contained area. Oils trapped within the wood burn, turning into smoke alongside wood particles and fly ash. As the smoke cools, it liquefies, combines, and then solidifies into a gummy, grayish or yellowish substance that’s sometimes liquid and other times more gelatinous in texture.
Some forms of creosote are also thickly solid. Many people compare its look to tar, leading to the somewhat inaccurate nickname “tar buildup.”
Creosote’s Multiple Dangers
In keeping with its unsightly appearance, creosote can be extremely dangerous. Worse still, as creosote develops inside the chimney flue (or air passagey,) it actually feeds off itself: existing creosote traps more gasses and oils, leading to the generation of more creosote. But the greatest danger lies in creosote’s flammability. Under the right conditions and when exposed to hot enough fires, creosote can itself combust, leading to a fire inside the chimney flue.
The most dangerous form of creosote is known as “creosote glaze.” This occurs when new layers of creosote are formed so quickly that the layers beneath it have no time to fully dry out. The layers on top act as insulation for the layers beneath, and eventually the creosote solidifies into an almost rock-like density.
Removing Creosote Is Hard Work
Creosote can be very difficult to remove. Many professional fireplace cleaners and chimney sweeps will often resort to chemical agents to help break down the creosote’s composition, the better to remove it from the chimney. It’s dirty, often dangerous work that requires strict precautions, and can often become very expensive.
How To Safely Remove Creosote From Your Chimney Flue
Probably the best weapon against creosote is vigilance. Regularly examining your chimney firebox and flue for creosote’s early residue will let you act proactively to stop its spread.
Hiring a professional chimney sweep to clean your chimney flue can often be expensive and time-consuming as you research which local chimney sweep offers the best service. For do it-yourself enthusiasts, there are a variety of solutions, powders, and tools to help first break down creosote and then safely, effectively remove its residue. These tools range from brushes and scrapers to whips and special stripping implements.
Fireplace experts do recommend having a professional chimney sweep or other fireplace expert (fire marshal, et cetera) evaluate your chimney and fireplace before undertaking a creosote removal project. Make sure to exactly follow all safety precautions, including wearing protective eye wear, gloves, and breathing masks. Creosote is a known carcinogen (cancer-causing substance) so taking all precautions is critical for safety.