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Do Those Chimney Sweeping Logs Really Work?

Q: Lately I've seen two different brands of logs you can buy called "Chimney Sweeping Log" and "Supersweep" that supposedly clean your chimney. How can the logs I'm burning CAUSE creosote buildup in the flue, while these other logs are supposed to REMOVE it? What is so magical about these logs? Or do they even work? If so, is one better than the other?

SweepyA: It isn't really the logs that are supposed to do anything, it is the chemicals they're impregnated with, and chemical products that claim to clean or assist in cleaning chimneys are nothing new. In fact, there are actually some chemical products that are used by professional Chimney Sweeps in conjunction with mechanical cleanings. Specifically, in some extreme situations, a chimney can develop third-stage, glaze creosote that is so hard that it cannot be removed by mechanical brushing alone. In these cases, certain liquid chemical catalysts may be sprayed directly onto the glaze to alter its chemical composition, turning it into a brittle or powdery condition so it can be swept out.

From what we've read and observed, the "Chimney Sweeping Log" and "Supersweep" products currently being marketed likely contain some sort of similar chemical catalyst. If they do, here's how they would work: the chemical would be carried up the flue by the rising exhaust gases, where it would deposit on the glaze in dry form and, over the course of several subsequent fires, break it down so it could be swept out.

We have a couple of problems with the marketing of these logs: first, their names are misleading. You might expect a product called The Chimney Sweeping Log or Supersweep to sweep your chimney, or at least perform an equivalent function. The actual claim in the fine print is that the chemical contained might reduce creosote by as much as 60%. Second, we have not found chemical catalysts to be of any use whatsoever on first- or second- stage creosote deposits, which comprise about 90% of the deposits we find in chimneys (glaze deposits are an extremely rare occurance). Third, even if your flue was coated with glaze creosote and the chemical in the chimney sweeping log broke it down as much as 60%, it would still represent a considerable safety hazard until it was physically removed by sweeping.

The Washington Public Fire Educators Association has come to a similar conclusion, and published the following position paper:


Chimney Sweeping Logs:
The use of chimney sweeping logs (and similar products) alone is not an adequate substitute for mechanical chimney cleaning and inspection because it does not provide for the same level of protection to the chimney system.

Vital Points:
Each time you burn wood in your fireplace or woodstove, tar and creosote are formed and over time, will build up on the inside of your chimney. This build-up is highly flammable and can ignite causing a chimney fire. To prevent chimney fires, the fire service has long recommended having your chimney cleaned and inspected annually by a licensed professional. But now, a new product called the “Chimney Sweeping Log” has many citizens wondering whether an annual mechanical cleaning remains necessary.

The manufacturer of the Chimney Sweeping Log claims that the product contains “specially developed minerals” that act to reduce deposits of tar and creosote thus reducing the risk of chimney fires. To use the product, you simply place the log in your fireplace or woodstove and allow it burn for roughly an hour and a half. The product’s website boasts that “the burning of a single Chimney Sweeping Log can reduce build-up by up to 60%”.

Washington Public Fire Educators (WPFE) is concerned about these claims. While we won’t dispute what these fire logs will do, we feel that it’s vital to address what they won’t do. If these logs manage to loosen creosote so it flakes off the flue walls as the advertisements claim, where does that creosote go? It either catches fire as it flakes off and increases the potential for a chimney fire through the intense burning, or it falls to the bottom and collects on the smoke shelf, thus causing a future hazard.

WPFE believes that the safest and most effective chimney maintenance is achieved through annual inspections and mechanical sweeping.

The basic task of a chimney sweep is to clean chimneys. The cleaning process includes 1) removing the hazard of accumulated and highly combustible creosote produced by burning wood and wood products, 2) eliminating the build-up of soot in coal- and oil-fired systems and 3) removing bird and animal nests, leaves and other debris that may create a hazard by blocking the flow of emissions from a home heating appliance. In addition to the cleaning, chimney inspections often reveal hidden problems within the structure that could be potentially dangerous such as breaks or breaches in the flue.

Mechanical sweeping of chimneys not only removes layers of creosote from surfaces, it also eliminates the resulting debris from the chimney, fireplace, or woodstove. Many chimneys are not constructed in a straight path from the firebox to the outside. If chimney-cleaning products perform as claimed and cause debris in the chimney to fall, that debris must still be removed from the smoke shelf, baffle, catalytic combustor, or offset in order to ensure a safe and properly functioning chimney.


Here's what The Chimney Safety Institute of America has to say:

“The use of these products alone is not an adequate substitute for mechanical chimney cleaning and inspection because it does not provide for the same level of protection to the chimney system.”

(The Chimney Safety Institute of America is a non-profit, educational institution focused on the prevention of chimney and venting hazards.)


Sweepy August, 2004: The US Govt. Weighs In

A Federal Court recently found that the claims by the manufacturer of the "Supersweep" product that the logs removed creosote were false and that the name "Supersweep" was misleading. The Court's order expressly bars the manufacturer from future use of any of the following claims in connection with their fire log product:

"helps eliminate dangerous creosote in the chimney"

"helps prevent chimney fire"

"aid[s] in the loosening and breaking away of hard, scaly or glazed creosote deposits"

"lowers the combustion point of the creosote and soot deposits in a chimney flue by up to 500 degrees F"

As a result of this ruling, the manufacturer may no longer call the product a "chimney cleaning log."

Source: Alternative Energy Retailer Magazine


September 14, 2006 - A Consumer Testimonial?

Q: I certainly agree that the log doesn't replace a certified Chimney Sweep, however after having a new steel liner installed, I now use 2 logs per season, and after burning 4.5 cords of wood only have to have my chimney cleaned once a year instead of twice. You failed to mention that when a steel liner is installed by a certified professional, that the creosote can't fall on anything, cept into the fireplace. Where it can be placed into a steel bucket and taken away and disposed of. Lets be honest here-the log is a money-saver (1 cleaning per season-instead of 2). Nothing wrong with that!

So, instead of taking a negative view of this product, why not explain to people how it can be advantageous? If used properly, and not as a replacement for a thorough cleaning once a year- especially if your fireplace is up to code.!!!

George Hill

Sweepy Hi George,

It seems your closing point is already more than covered in the posts above, but I would like to address your earlier statement that any creosote that falls from the flue would land harmlessly into the fireplace, where it can be removed.

The Sweeping Log manufacturers admit that, at best, only about 60% of the creosote in the flue might dislodge, which, even in that best-case scenario, would leave 40% of the creosote still coating the flue. What if there's a fire going when the creosote dislodges? Wouldn't it fall into the fire, where it would likely ignite? Creosote burns at extremely high temperatures (much higher than wood), so wouldn't the presence of a raging creosote fire in the fireplace increase the likelihood that the creosote remaining in the flue would ignite?

It seems to us that, even if the Sweeping Logs do what they say they can (and the courts and others seem to have their doubts), their effect would be to INCREASE the chances of a chimney fire.

A final point: you mention in your letter that you began using the Sweeping Logs after you had a stainless steel liner installed. Properly sized liners are known to dramatically decrease creosote formation in the flue, so I wonder if the Logs even have anything to do with your less-frequent need for cleaning. None of our chimney cleaning customers with properly lined chimneys need their chimneys cleaned more than once per year, and I'm betting you won't either - with or without the Sweeping Logs.


January 29, 2007 - Another Consumer Experience

Well, I bought one of these logs and used it in my woodstove. I took down my stovepipe, and it was still full of creosote.

This thing doesn't work. I might as well have thrown the money I paid for that stupid log in my stove and burned it (maybe the $15.00 would have made the creosote disappear).

All those claims about the creosote sweeping log are bologna. I'll never buy another one.

Pat Coston


Sweepy Update: February 11, 2008: The Canadian Competition Bureau [Canada's version of the US Consumer Products Safety Commission] ordered two companies to stop making unsupported marketing claims for their chimney logs and cleaning products.

The watchdog said the companies, which are part of the umbrella group Imperial Manufacturing Group, made performance claims that the fire logs and chimney-cleaning products would reduce creosote. The products were also touted as a method of preventing and eliminating chimney fires. These claims were not supported by adequate testing, the federal agency said.

The products under review included:

The Supersweep Chimney Cleaning Log.
The Imperial Chimney Cleaning Log.
The Kel Kem Chimney Creosote Cleaner.
The Kel Kem Creosote Conditioner.

The companies were ordered to change their marketing promotions and labels and to pay a penalty of $25,000.

"Advertisers have a legal obligation to ensure that consumers are not misled when making their purchasing decisions," said Andrea Rosen, Acting Deputy Commissioner of the Competition Bureau, in a release.

"Watchdog sends chimney-cleaning product claims up in smoke"
Monday, February 11, 2008
CBC News


October 26, 2010 - Why aren't these logs working?

On October 15, 2010 I had my chimney swept (do it every year)--by Hutch's Chimney & Stove Service out of Angelica NY. On his report he wrote:

"The flue has major 3rd stage creosote buildup. 3rd stage must be removed before chimney is used. Using the chimney in its present condition poses a potential hazard"

I have burned a CSL log every two weeks during the winter months when the stove is in use. I burned 10 CSL logs in that stove the last winter.

Why are the logs not cleaning the chimney?

Please advice me what to do next.


Bernie Lubberts

Sweepy Hi Bernie,
First, I suggest you read the other posts on this page, to get a better picture of what the CSL logs can and can't do. Next, I advise you to call your Sweep back and schedule chemical glaze (3rd stage) creosote removal treatments.

Finally, you need to look into why you're forming 3rd stage creosote. The three most common causes of glaze buildup are burning green or wet fuelwood, smoldering the fire, and oversized chimney flues.


November 30, 2011 - Used CSL, Had Chimney Fire!

I was going to buy a Chimney Sweeping Log again this year. But I found nobody wants to sell them anywhere. So I reviewed your opinions online. I must say, my experience reflects what I read. I had a helluva chimney fire after using a CSL. Luckily, the fire department arrived in time. I believe the fire happened because I didn't vacuum my stove pipe and elbow after using the log. Now I believe that the CSL is not sufficient to protect my house. I will contact a chimney sweep in my area.

Peter Hastings
Chicago, IL


Sweepy The bottom line: Whether you choose to use products like The Chimney Cleaning Log and Supersweep or not, have your chimney cleaned and inspected by a licensed professional at least once a year.


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