Everything You Need to Know About Chimney Soot | Do you know what chimney soot is? When woods burn in a fireplace or stove, it creates combustion byproducts such as ash, smoke, and wood particles. When air currents bring these contaminants away from the fire, they will settle as creosote or soot deposits in the stove pipe, fire compartment, or chimney. And these deposits are dangerous when they block airflow or get burnt at a later time. When you notice a build-up of soot around or in your fireplace, this is a sign that there is an underlying problem.

So, what is soot? Are there any differences between soot and creosote? For those of you who are not familiar with it yet, here is everything you need to know about soot.

What is Chimney Soot?

What is chimney soot? Soot is a powdery residue of unburned carbon particles. It is usually black or brown that looks like a smudgy smoke or dust that settles or surfaces. You can easily clean soot by wiping it off or brushing it at first. Unfortunately, soot will gradually accumulate in layers in a fireplace, chimney, or stovepipe. If soot deposits accumulate from time to time, they can reduce airflow up to 30% so that the flue does not properly vent. This condition may cause smoke to go back in a home. And this surely leads to various health problems.

This black or brown powder is formed because of incomplete combustion of coal or wood in a confined place, such as a fireplace, chimney, and stovepipe. Therefore, soot can be referred to as the byproduct of fireplace combustion. This residue is formed in a temperature lower than 284 degrees. When fuel like charcoals or woods burn, they break down and settle as a powdery dust. This is what is called soot. It is also responsible for giving a fire the reddish orange or yellow colour because it radiates colours in the red to yellow spectrum.

Soot is also known as carbon black and lamp black. This residue forms a common ingredient in the making of shoe polish. Besides powdery, soot can also be oily or flaky in textures. Because of its texture and colour, soot will likely stain or darken surfaces. It tends to stain walls, ceilings, ventilations, floors, clothes, and even skin. It is not even necessary in a large concentration or proportion for the soot to stain surfaces.

Since it is not completely burnt, creosote is slightly sticky as well as tends to stick to surfaces, such as chimney flue and exhaust pipes. Since both soot and creosote blocks the airflow, they tend to cause numerous problems.

What is the Difference Between Soot and Creosote?

While soot is a black or brown powdery residue of unburned carbon particles, creosote is a tarry residue that condenses from coal or wood particles, gases, hydrocarbons, and other airborne debris. These substances cling to surfaces when they cool, creating layers of flammable deposits. Creosote may be dry, flaky, and thick layers of shiny and hardened black gooey substances. It may also be crackling when you touch it.

While soot is formed due to incomplete combustion of wood or coal, creosote forms as cold gases so that deposits happen when the chimney temperature is cool as well as when the air is not hot enough to bring the particles out of the chimney. Restricted air supply is also possible to make the sticky particles to settle.

Are Soot and Creosote Dangerous?

You should not underestimate both soot and creosote even though they are just in a little amount. There are so many chimney soot dangers. Both soot and creosote naturally accumulate in a flue and fireplace. This is why it is important for you to check your chimney regularly, at least once every year. You are suggested to call a chimney service to check the chimney at your house and sweep away any excessive deposits.

Though you can take some steps to minimize deposits, you cannot avoid finding soot in fireplace hearths and creosote in wood-stove chimneys since they naturally accumulate. If you hire a chimney service to clean them on an annual basis, you can reduce the risk and danger of a harmful deposits. Creosote and soot are the bydproducts of burning woods or coals. Both naturally accumulate in the flue liner of a wood stove and fireplace.

However, creosote is unique because of most tars produced due to incomplete combustion of coal or wood. The only similarity of soot and creosote is that they are both dangerous and harmful for your health. Soot and creosote are inhalation and topical dangers. People who work in the fireplace maintenance industry must already know this. So, while these dirty substances naturally happen, they can lead to a variety of health problems for homeowners. Not to mention they can cause fire inside your flue if you ignore the deposits.

Problems Caused by Soot and Creosote

Due to the blocking tendency, soot and creosote can lead to some issues. Here they are.

  • A blocked or clogged chimney will not be able to smoothly draw in air. Therefore, fires become smoky as well as consume a lot more fuel.
  • If creosote builds up in a chimney in a large amount, this is probably the cause of chimney fires. This is one of the reasons why you need to regularly check and clean the chimney at your house.
  • The floors will get messy and dirty if soot falls back into the house through the chimney. This occurs when the byproduct builds up in the chimney. And because of the back-suction of air, it is pulled back in the house. This residue can stain floors and rugs and it will be very challenging to clean it up.
  • Soot can surely be dangerous for your health since it is a carbon byproduct. You are at risk of respiratory infections and lung diseases if you inhale it frequently in a large amount. This can happen because soot contains PAHs or Polycyclic Aromatic Hydrocarbons in the form of gas. Besides being harmful, it is also hard to treat when someone affected by a serious illness or infection from this byproduct.

Watch for the Warning Signs

As it is said before, a soot stain is a warning that there is something fishy and your chimney system does not properly function. You should consider it as a serious warning to have your fireplace and chimney checked when you notice any smoke residue appears on your fireplace mantle. It is also a warning when there is a dark fluid drains down the side of your chimney cap.

How to Reduce the Risk

In order to reduce the risk of health problems caused by chimney soot, regular maintenance will be really helpful for your whole burning system operate at peak performance. Since soot is the natural residue of the combustion of all wood-burning stones and fireplaces, a little amount can show up in the firebox with each fire. Though a little bit of this residue is normal, there are abnormal spots at your home where if it appears, then it is an indication that you have a dangerous situation growing.

So, as it is said before, it is crucial to have your fireplace and chimney inspected on a regular basis. You should call a chimney service to check and clean it every year.


The most reliable and most effective way to get rid of soot and creosote is regular chimney maintenance. The professionals will scrub off the deposits with a stovepipe brush or chimney scrubber. They may also disassembly the stovepipe, but brick chimneys are fixed so that professionals usually clean it by scrubbing upward from the firebox with a wire brush and downward with a chimney brush.

Homeowners sometimes want to build a hot fire to burn out the creosote and soot deposits. However, this not suggested at all. It is because the creosote and soot may burn as an extremely hot fire in the chimney. If this happens, it can damage your chimney and house structure and you surely do not want this to happen. Do not ever try to clean your chimney by using fire to burn soot out. Build-up in a flue is mostly from smoldering fires drafting through a cool chimney.

If you properly insulate the flue liner with a liner and fires are allowed to burn at proper temperatures, then you can minimize the dangers of soot and creosote. Keep in mind that if your chimney has a build-up of 1/8 inch, it increases the hazards of a chimney fire. If a fire happens in a chimney because of combustible deposits, then the most frequent result is a damaged flue and fire risk spreading to the walls behind the chimney. The embers can even reach the rooftop.

Important Tips

It is highly suggested to have your chimney inspected annually by a qualified chimney sweep service in order to prevent harmful chimney fires. Between inspections, you can prevent and reduce the dangerous accumulation of creosote and soot by using soot and creosote remover products. How often should you use the product? In order to decide how often you should use the soot and creosote remover, you need to keep in mind the type of woods you burn, how hot the type of wood you use burns, and how often you use your wood-burning appliance.

How to Keep Soot Out of Your House When Cleaning Your Chimney

Since soot is a powdery residue, it will fly free and coat everything in your house as you are trying to clean your chimney. So, take these preventative actions to keep soot out of your house when you are cleaning your chimney.

  1. Clean the area surrounding your wood stove or fireplace. Get rid of decorative elements on the hearth as well as the mantel in order to make sure adequate workspace without having to be worried about breaking or dirtying items.
  2. Roll up the rugs and carpets in front of or close to the stove or fireplace. If possible, move your rugs and carpets to another room.
  3. Cover the furnishings, furniture, and floorings around the fireplace or stove with plastic. As an alternative, you can also use sheets or blankets to cover the furniture and spread paper grocery bags or newspapers across the floors.
  4. Create walkways that lead from whichever door you use during the chimney cleaning process to the stove or fireplace. You can use plastic sheeting, newspapers, or other protective covers. This can prevent spreading the soot, creosote, or other dirt that can damage the floorings without you have to pause and take off your shoes.
  5. Turn off any portable or ceiling fans and any central heat or air so that they will not involve during the cleaning process.
  6. Close the stove or fireplace doors in order to prevent creosote and soot releasing from entering the room. Or you can use a sheet of plastic that is big enough to cover the fireplace doors. Also, use duct tape to seal every edge, preventing dirt and creosote from entering the room.
  7. Watch the clock or set a timer once you have cleaned your chimney. Wait at least 30 minutes to make sure the dust and creosote settle down before you start the cleaning process.
  8. Carefully unseal the stove or fireplace, as well as when you open the fireplace doors and uncover the plastic sheet. Immediately fold up the material and throw it away in a trashcan or plastic bag.
  9. Scoop up dirt and creosote that fall to the bottom of the chimney into the stove or fireplace. You can do so by using a dustpan or stiff-bristled brush. Use a vacuum with a special filtration system in order to vacuum remaining ashes and dust. Throw the debris away and remove the remaining protective sheets from the floors and furniture.

That is everything you need to know about soot. As you can see, it is very important to clean chimney soot and creosote because they are harmful.

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