Archive for the ‘soot’ category

Natural Fireplace Maintenance

February 8th, 2013


We have a natural fireplace, not gas. Can you tell us the maintenance we should be doing on our fireplace? What is the maintenance on a gas fireplace? Should we be having our chimney cleaned out by a professional? Is this necessary?



F005 - Masonry FireplaceFor a typical wood burning fireplace, you should have the chimney cleaned and inspected every several years. The cleaning depends on how often you burn wood. If you burn most weeks, clean the chimney every year. If you burn a few times per year, clean the chimney every few years.

With a gas fireplace the maintenance is limited because the products of combustion are relatively clean. The fireplace logs should not be producing excessive soot and they should be checked along with the chimney flue every couple of years.

With either fireplace, you should also make sure the damper is closing tightly when you are not in use. You should make sure the damper opens fully and latches open when you build the fire. Outside there should be no bird or animal nests in or around the chimney.

For a masonry chimney, the cap should be solid and overhang the structure of the chimney. The structure should be solid without salt stains or surface spalling. For a framed-in metal chimney, it should have a cap that directs water away from the flue with limited rust. The box should be in good condition just like the siding of your home.

With either type of chimney, I think it is important to have a rain cap on the flue. They keep water and animals out of the chimney flue. When in doubt about chimney or fireplace issues, have a professional check it out.

Soot and Sawdust Removal

June 1st, 2010


I think I have soot stain problems in my house after reading about them on your website. I have all-electric house heating, made up of baseboards and storage units. My wife loves her candles as much as I love my woodworking, but both cause dust and soot. Can you suggest a cleaning solution for the ceilings and walls? Also, can you recommend any air filtration solutions to help the problem? Thank you.


The best solution for the soot stains is to stop burning all candles. Well, OK – I do ‘let’ my wife burn a few high quality candles, and she keeps the wicks trimmed to about 1/4″ length. A high quality candle and a short wick will reduce the soot produced. We don’t ever use the nice, smelly candles in a glass jug. They are great soot producers because there is a lack of oxygen in the jug and the scent comes from something released into the air.

Removing the soot is a problem because it is such a fine particle and it tends to stick to surfaces with a magnetic charge. You can try a dry sponge – it’s a large, soft, rubbery sponge that absorbs soot. They are used for fire restoration work and you can find them in larger paint departments. After wiping with a dry sponge, clean the area with a strong detergent using lots of rags and water/detergent changes.

Soot is very hard to remove. When re-painting, prime the surface with BIN to cover the soot. BIN is available in most paint stores and is also used in fire restoration.

There is no filter that will remove soot. For the woodworking dust, I suggest you try to control it at the source. Use a vacuum system with a great filter and seal the woodworking shop from the rest of the house. Seal any heating ductwork in the shop, particularly the return ducts that may suck in the dust from the air. On a forced air furnace, use the best quality paper filter you can find to remove the sawdust.

Shadowing, Ghost Stains

February 17th, 2010

What causes “shadowing” on house walls? I always chalked it up to soot from candles, but I recently had a realtor call me about a house that had shadowing on studs, ceiling truss members, and nails/screws in the drywall. The house was built in 1995 and is a typical ranch-style in West Michigan. There appears to have been a “zero clearance” fireplace that may have been wood or gas. Any ideas?


You have it right, most gray stains that outline framing and fasteners on drywall are caused by soot from combustion. The soot is often from burning candles. The worst candles are the good-smelling ones in a glass jug because the flame lacks Oxygen for combustion. A gas fireplace can also cause soot inside a home.

The soot collects near framing and fasteners on outside walls because these areas are slightly cooler and the air slows as it passes by, depositing soot. You will also find soot on horizontal surfaces and around pictures where air flow changes direction.

Check out my free article:

Soot, Ghosts and Ugly Stains