What is Soot?

Mary McMahon
Mary McMahon

Soot is a fine black to brown powder formed through incomplete combustion. The process that forms it also makes it slightly sticky, and it can be found clinging to things like chimneys and exhaust pipes as a result. In addition to being a byproduct of the combustion process, soot can also be useful; it has been utilized for centuries as a source of pigment for inks and dyes, for example. Many consumers are familiar with some form of it, since combustion is such a common process in daily life.

Factory pollution became a large problem in cities with industrial growth.
Factory pollution became a large problem in cities with industrial growth.

In order to form soot, an object must be burned at a comparatively low temperature with a reduced supply of oxygen. As the fuel burns, it breaks up into small particles; in the right conditions, these particles include soot, which will settle out as a dark powdery deposit. For an example, a person can try holding a heat-safe glass over a lit candle for a moment; a streak of black material will appear where the flame came into contact with the glass.

Rubber gloves should be worn when cleaning soot.
Rubber gloves should be worn when cleaning soot.

This material is also called lampblack or carbon black. Carbon black is used in the vulcanization process to treat rubber, and it is also used in a wide range of pigment, paint, and dye products, ranging from crayons to fine ink for fountain pens. Historically, people also used it in cosmetics, or as part of camouflage paint. It's also used in toners for laser printers and copiers.

Like some other products of combustion, soot can be harmful. Incomplete combustion promotes the formation of dioxins and other compounds which can be toxic, and particulate matter can be harmful to the lungs. During the Industrial Revolution, this pollution from factories was linked with serious health problems in the neighboring community as people routinely inhaled it, causing irritation in their lungs.

In things like chimneys, soot can also create clogs, causing a range of problems. A clogged chimney will not draw as efficiently, so they can tend to cause smoky fires or inefficient use of fuel. This material can also be dislodged from a chimney, causing a gust of black, sticky particles to enter a house. It can also cause chimney fires if it is allowed to build up, which is why it is important to regularly clean chimneys, stove hoods, and other piping that is designed to deal with the byproducts of combustion.

Use a vacuum to clear away soot from the firebox.
Use a vacuum to clear away soot from the firebox.
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

You might also Like

Readers Also Love

Discussion Comments


@anon41741-- It sounds like your turbo has loosened. It might also have to do with fuel pressure, but that's not as common as turbo issues.

You will probably have to replace the turbo. I wish there was a cheaper and easier option, but if there is weeping soot emissions because of a loose turbo, it'll only get worse after this.

Try renewing the turbo seals and see if there is improvement. If not, like I said, you will probably have to buy a new turbo.


@anamur-- That's true. Many women in India still make their own kohl this way. They usually burn some ghee or almond oil or castor oil with a metal lid to collect the soot. Then they mix the soot with a little bit of oil to make it easy to apply.

It's actually very easy and also completely natural.


@anon3815-- I heard from my mother that soot can be used to make organic kajal (eye kohl) at home. Apparently, this is how my great-grandmother would make her black eye makeup. I have no idea how it is made though. My mom doesn't quite remember the process and recipe. If I had the recipe, I think it would be cool to try.


What is the literal combustion process of fire?


How do you get rid of wet soot that is weeping?


you can put some chemical compounds in your fuel airliner to make it cheaper and obtain carbon credits in exchange. As a bonus, you also have a chance that this soot will be harmful to bees and most living thing on earth.


How do you get rid of wet soot that's weeping?


what are the other uses of soot aside from the information stated above?

Post your comments
Forgot password?