Part of enjoying a fire is contending with the mess that comes with it. Wood fires naturally produce ash, soot, creosote, smoke, and more. The chimney system works constantly to vent these harmful byproducts from the home. However, over time the chimney can become coated with soot and creosote. When soot and creosote are left to build up in the chimney flue, it can lower efficiency. This causes increased fire risks and health concerns. The Chimney Safety Institute of America (CSIA) and the National Fire Protection Association (NFPA) routine chimney sweeps and annual chimney inspections in order to maintain the highest levels of chimney safety and efficiency.

Soot Versus Creosote

Soot is a powdery substance that is easily removed by standard tools during a chimney sweep. Creosote is black or brown like soot, but appears crusty or flaky. It is made up of tar and melts as it heats up. It appears drippy and sticky, then it cools into a hard and shiny mass. Creosote is highly flammable and becomes more so as it heats and cools repeatedly. As creosote continues to buildup in the flue, and transforms into this hard mass, it only worsens, resulting in a flue fire.

Glazed Creosote

When creosote has been left in the chimney flue long enough to buildup and become shiny and hard it is called glazed, or level three creosote. Level three is considered highly flammable and dangerous. If you have a level three buildup your chimney will not pass a CSIA chimney inspection and failing to keep your chimney working properly will shorten its life.

Creosote in the chimney can restrict airflow, causing even more creosote to build up in the chimney flue. When airflow slows down in the chimney, the draft doesn’t pull the vapors and smoke up and out of the chimney properly. As the airflow slows, the soot, creosote, and sparks stall in the chimney along with the air. The sparks can easily ignite the creosote on the flue walls.


If your chimney expert recommends glazed creosote removal, this is a serious problem that should be addressed. Glazed creosote removal is more complicated than a standard chimney sweep in which a technician cleans away soot and creosote with brushes and a vacuum system. Glazed creosote can’t be brushed away, however, Pristine Sweeps specializes in its removal. All of our certified chimney sweeps are trained in the use of specially-formulated chemical cleaning products designed to remove glazed creosote. These products create a reaction that changes the texture of the creosote for easier removal. During your chimney appointment the glazed creosote becomes flaky and easier to remove with chimney sweeping tools.


It is important to hire a professional to remove dangerous creosote from your chimney in order to keep your family safe and warm. This type of service takes more time and money than a standard chimney sweep and can be completely avoided. Creosote is a natural byproduct of your fire, but it doesn’t have to be a problem. Some conditions encourage a creosote buildup including restricted air supply, improper fuel, and cool chimney temperatures.

To find out more about creosote and chimney fires click here or call Pristine Sweeps at 206-574-8414.