Creosote is the black residue that is left in the chimney from wood that has been burned incompletely. If the smoke from the chimney is cooled down to 250 degrees Fahrenheit, the gas will liquefy and form a substance known as creosote, which is the main cause of chimney fires.
There are several different forms of creosote. For example, they can be present in liquid form, and will easily ooze out of any chimney openings or be in a more solid form and plug up pipes. If the creosote is 1/8 inches thick, you should consider scheduling a chimney cleaning as soon as possible, and if the accumulation has grown to 1/4 inches thick, then you should not use your chimney until it has been cleaned.
This article will explore the 3 different stages of creosote and how to remove it.
Minor Buildup Otherwise Known as First-Degree Buildup
First-degree buildup is most ideal, and is generally unavoidable. Homeowners will find first-degree buildup if their chimney is functioning properly and able to provide an adequate supply of air or if they own an open chimney. The heat produced from the flame will be able to easily fly up from the chimney, and very minimal creosote is produced as a result.
First-degree creosote is compromised mainly of soot. It can be easily removed from the chimney with a chimney brush, and does not cling onto the chimney surfaces at all.
Moderate Buildup Otherwise Known as Second-Degree Buildup
If you don't have an open chimney or a structure that is able to provide an adequate air supply, then you can expect to see a moderate buildup. This generally happens when the air supply is restricted and there are obstructions that are preventing air from entering the chimney properly. Wooden stoves and chimneys that have glass doors are typically more prone to developing moderate buildup of creosote.
Second-degree buildup of creosote looks slightly different than first-degree buildup due to the fact that the soot content is diminished. Second-degree buildup contains shiny black flakes that are present in high volumes. These flakes are tar-like and tend to be rather dry. As a result, they are much more difficult to remove from the chimney.
This type of creosote will easily plug different openings, and is much harder to remove. Using only a chimney brush may not be sufficient. Also, a lot more elbow work is required.
Severe Buildup Otherwise Known as Third-Degree Buildup
Severe buildup, or third-degree buildup, of creosote is considered to be the worst-case scenario. This typically happens when the chimneys are unable to provide adequate air and the combustion reaction is incomplete. You can expect severe buildup if the house is small and unable to draw in sufficient volumes of air, when using unseasoned wood, if the flue is oversized, if the chimneys are not properly insulated and if you have wood stoves with improper settings for the air controls.
Unlike first-degree and second-degree creosote, third-degree buildup looks a lot different. It is similar in appearance to tar coating, and is basically concentrated fuel. Most of the time, this type of buildup gets extremely thick and hard, and will be able to easily burn if it catches fire. When heated up, this type of creosote can fluff up and have a sponge-like appearance.
While the sponge-like appearance creosote is easy to remove, additional tar-like substances can get into the pores of the sponges causing a bigger problem and headache. This is likely when you'll need a specialist to come and ensure it is all safely removed.
To prevent the accumulation of creosote, you want to make sure that the structure of your chimney can supply an abundance of combustion air. This will encourage a hotter and cleaner-burning fire, and reduce the amount of creosote that is produced.
If you find that you have a lot of creosote building up in your chimney in a relatively short period of time, you should be concerned with not only whether you have been cleaning the chimneys properly, but also whether the structure of the chimney needs to be repaired or whether there are any underlying problems that need to be addressed. Discover more here on how professionals can further address creosote.