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Tell Me About Creosote

If you have a wood-burning fireplace or stove, Fire Safe Chimney Sweep technicians will focus on removing creosote deposits when we come to your home for a chimney sweeping appointment. And that part of our job is extremely important — by removing creosote, we’re working to improve both the safety and performance of your system.

If you’re unfamiliar with creosote, what it is and what its presence does to your chimney system, here’s a quick primer.

Creosote is a highly flammable byproduct of burning. Although some creosote buildup is normal, it must be kept at low levels because it is a fire hazard.

Creosote is a highly flammable byproduct of burning. Although some creosote buildup is normal, it must be kept at low levels because it is a fire hazard.

What Is Creosote?

Creosote is a dirty, smelly and highly combustible condensate that develops and builds in your chimney, particularly on your flue walls, as you use your wood-burning heating appliance. It’s mostly ash, condensed gas particles and unburned fuel, and depending on the stage it’s in, it can be powdery and velvety, crunchy and flaky, syrupy and gloppy or shiny and rock hard. We describe creosote in stages of development: Stage 1, Stage 2 and Stage 3 creosote.

Stage 1 is finer and more powdery, and Fire Safe techs remove it during a routine sweeping appointment with our specially designed brushes and vacuums. Stage 2 creosote is generally puffier and flakier, but it can still be brushed and swept effectively. Stage 3 creosote is often called “glazed” creosote, and if that develops, it’s a much bigger headache. Glazed creosote looks like it sounds — it’s a hard glaze, sort of like the coating on a candy apple, but black — and its removal requires the use of chemical agents to break it down.

How Does Creosote Form?

Since creosote is basically condensate, it forms, like you’d think, via condensation. The heated air, gases and particles from your fire rise in the flue and hit the comparatively cooler walls, causing gases to condense into liquid. That liquid dries, and you have creosote deposits. Those build up and thicken as you continue to use the fireplace or stove.

Why Do I Need To Know About Creosote?

First, creosote can be dangerous. Since it’s highly flammable, the thicker and more creosote you have, the higher the possibility of a fire hazard there is. Creosote deposits can also affect the draft in your chimney by negatively impacting air flow, and that makes it more difficult for your chimney to do its job of routing byproducts up and out of your home. Acids in those deposits can also wear at your flue liner and your masonry. Perhaps less importantly, but still worth thinking about, creosote can make your fireplace stinky and dirty.

How Do I Limit The Amount Of Creosote In My Chimney?

Regular chimney sweeping is the best thing you can do to keep your chimney free of creosote. But day to day, there are a few practices that can help you avoid excessive creosote or developing glazed creosote

– Make sure to completely open your damper every time you light a fire

– Always use seasoned or kiln-dried firewood, or dry your own wood for at least a year before you burn it

– Steer clear of burning trash, Christmas trees or anything else that isn’t seasoned firewood

If you want to know more about creosote or safer/better burning practices, Fire Safe Chimney Sweep is always here to help. Just give us a call!