What You Need to Know About Black Glass

Fireplace with glass doorsFor there to be fire, three things are required: oxygen, fuel and heat. Remove any of them from what’s known as the “fire triangle,” and you can’t start a fire. This is the simple part of fire, but it gets more complicated, particularly where the quality of the fire is concerned. Just because you see a flame doesn’t mean the fuel is burning optimally. In the world of fireplaces, poorly burning fires can create a variety of problems, one of them being black glass.

If your glass fireplace doors have turned black, it’s because excess soot is being produced when you burn a fire. In the majority of cases, this over-production of soot is due to a problem with either the oxygen or the fuel part of the fire triangle.

Black glass on a wood fireplace

If the glass doors on your wood-burning fireplace have turned black, there are two likely culprits: improper air flow (draft), and unseasoned (wet) wood.

When there is a hinderance of air in the firebox, logs burn weakly and produce excess smoke and soot. If you’ve ever seen a perfectly burning fire, you’ve noticed there’s surprisingly little smoke. As part of the fire triangle, the right amount of air is critical to creating a fire that burns hot and fully ignites the logs.

To solve drafting issues, first make sure your fireplace damper is in good working condition and that it is fully open when starting the fire and during the early stages of burning. A weak draft also can be caused by obstructions in the flue including excess buildup of creosote and debris such as small-animal nests, leaves and twigs. All these obstructions can be professionally removed by a chimney sweep.

Wood that isn’t completely dry will create large amounts of smoke and soot. Think of a forest fire – those huge billows and clouds of smoke are caused by the burning of wet fuel like leaves, foliage and damp wood. Your fireplace door glass will stay much cleaner if you burn only fully dry wood.

Black glass on a gas fireplace

Dirty fireplace glass doorThe air part of the fire triangle is also the problem when the glass doors on your gas fireplace start turning black. In this case, you have an improper air-to-fuel ratio – too much fuel (gas) and not enough air to fully combust the fuel.

Solve this problem by making sure the fireplace’s burner ports are unclogged and that the ceramic logs are positioned according to the appliance manufacturer’s instructions. Improperly positioned logs can impede air flow and create excess soot during a fire.

Black glass on a propane fireplace is also caused by the wrong air-to-fuel ratio. Improperly placed logs can be the reason for this as well as an obstruction or malfunction of the tank regulator. Obstructions in the flue and any other kind of drafting issues also can cause both gas and propane fires to burn inefficiently.

Cleaning the glass

Moist, balled-up newspaper and wood ashes do a good job in cleaning soot off glass doors. There are commercial cleaning solutions designed for this job that also work well. Once the doors are clean, follow the guidelines above to make sure they stay that way.

Chimney Solutions of Alpharetta, Georgia, is here to keep your fireplace running optimally and safely. We provide full chimney sweep services, chimney inspection and chimney repair. When it is time to have a chimney professional look at your fireplace, stove or chimney, call us at (770) 771-5501.

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