3 Things To Know About Black Glass (And What To Do About It)

After turning down your wood stove’s air control to “low,” you settled in for a good night’s sleep. When you woke up, the glass was black, and your morning was already off to a bad start. What can you do to keep your wood stove’s glass as clean and clear as possible?

Why it happens
“One thing to remember is that your stove is designed to burn fuel as efficiently as possible, with the minimum amount of harmful emissions,” says Ken Gross, senior product manager for Quadra-Fire. “The stoves produced today are tighter, don’t allow in as much air and provide a controlled burn. Smoke naturally will want to settle on the glass, because it’s the coolest part of the firebox.”

Quadra-Fire stoves all bring air along the front of the glass to help keep smoke away and create an efficient burn. All this to say: Please, do not be alarmed or assume something is wrong if black glass appears.

Uncovering the problem

Stove too big? Glass gets black faster: First and foremost, you should ensure your stove is sized right for the space you intend to heat. “If your stove is too big for the space, your tendency will be to build too small a fire, or run the stove on low all the time,” Ken says. “Then it will run too cool and not draft well.” The result of a stove that’s not drafting correct? Black glass.

“If you’re running the stove on low all the time, or opening windows because you’re getting too hot, that may be a clue that your stove is too big,” he says. “You should be able to run your stove on a medium to medium-high setting and only turn it down to low when you go to sleep.”

While solving this problem may be, it’s important to work consultant with a Quadra-Fire dealer that’s well-versed in helping homeowners select stoves. (Learn more about selecting the right stove for your space in our Wood Stove Buying Guide.)

Proper chimney & draft: This is the most important part of your stove or insert. All Quadra-Fire stoves use 6-inch diameter chimney and require a minimum height of 14-16 feet of chimney. If you still do not have a good enough draft, adding more chimney may be the solution.

Remember draft is the key, on stoves more chimney can increase the draft and on inserts running the liner all the way to the top and wrapping the first five feet with an insulation blanket designed for chimneys can increase the draft.

Wet wood can be a culprit: Just like a sense of humor or great taste, everyone thinks they have dry wood, but very few people actually do. “Invest in a moisture meter and only use wood with 18-20 percent moisture content,” Gross says. “Wood with a higher moisture content will make your glass blacken more quickly and severely.”

When testing wood, make sure you’re testing moisture in the right spot. Take a split piece of wood and insert the probes ¼-inch down, in the middle of a split side. Another way to tell if your wood is too wet? “If you see steam or bubbles coming from a log as it’s burning, it’s too wet,” Ken says.

Clean it up

“A clean stove is a happy stove,” Gross says, so he urges wood stove owners to make sure the glass is cleaned often. “It’s a part of ownership, just like sweeping out ashes, but it will be easier to clean if you do it regularly.”

Gross’s preferred method is to dampen a rag, dip it in stove ashes and use that to wipe off the glass. “The abrasion of the ashes helps remove the soot,” he says.

Or try this method to clean off glass, which can become part of you morning routine. “If you start a very hot fire first thing in the morning, that stoked-up fire can burn off a lot of soot that built up overnight,” Gross suggests. Another great resource? Our YouTube page has maintenance videos for all our wood-burning stoves and inserts that show step-by-step instructions for cleaning and simple maintenance checks.

Call your dealer: Struggling with black glass? Invite your local Quadra-Fire dealer over to check your stove’s size, draft and chimney configuration.

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