If your fire glass is turning black this is most likely soot being deposited on your fire glass due to the gas not burning completely. Typically this is seen with propane gas and is easily fixed. Once the problem is fixed, your fire glass can be easily cleaned to look like new.
Watching your beautiful fire pit glass darken and discolor can be a startling experience. But not to worry — your “burnt” fire glass is absolutely fine. The fact is that fire glass is non-combustible, and it hasn’t been treated with any chemicals or additives that can produce a residue on the glass.
What you’re looking at, actually, is a fine coating of black soot on the surface, which happens when the gas in your fire pit or fireplace isn’t burning properly. This is most common in fire installations that use liquid propane (LP) such as a propane fire pit.
Three Most Common Causes of Fire Glass Turning Black
1) Missing, Improperly Installed or Under Sized Air-Mixer (Propane Only)
Unlike natural gas that is clean and light, LP gas is a denser, heavier fuel that requires the addition of air to the gas. Otherwise, it won’t burn cleanly and will produce a black soot. This soot is visible as smoke rising from the flames that also leaves a black coating on your fire glass and fire pit. An LP gas air mixer will fix this problem by mixing additional air with the gas. This results in the most clean and efficient fuel source possible — and less sooting. Soot typically occurs when there is no LP air mixer present at all in a fire pit installation. Sooting can also occur when an air mixer is improperly installed or undersized for the burner.
To check if you have an air mixer installed, take a look at your fire pit’s piping. An air mixer will be found connected directly below the fire pit burner. Learn how propane air mixers work – including installation, testing and troubleshooting techniques.
Reducing the amount of air mixed with the gas changes the flame from blue to yellow. While this achieves the much DESIRED YELLOW FLAME, it also hinders the complete combustion of the gas resulting in a carbon soot residue.
2) Too Much Fire Glass Covering the Burner
The fire glass covering your burner should be just enough so the burner is not visible. If you have too much fire glass over your burner the gas is dispersed over a greater area resulting in incomplete combustion of the gas.
To fix this problem simply remove some of the fire glass until the burner is hidden just under the surface of the fire glass.
3) Wind Blowing the Flame
Even the slightest breeze can have a detrimental effect on the flame in your fire pit leading to sooting on your fire pit and on the edges of the burner pan. If you’re seeing soot around the perimeter of your burner pan then wind is the most likely cause. When the flame is moved around the burner pan by the wind it leaves some areas where the gas doesn’t burn or burns incompletely leaving a soot deposit behind. For a clean burn you want the flame to be consistently over the gas source.
FLAME GUARDS not only keeps the flame nicely centered in the fire feature, they also reduce the likelihood of sooting.
To fix this problem we recommend adding a flame guard to your fire feature. A flame guard is a small tempered glass wall which sits around your burner pan and acts as a wind buffer. Not only will the flame guard help reduce the sooting on your fire glass, it’ll also improve the look and appeal of your fire table.
How to Clean Soot Off Your Fire Glass
The good news is that no matter how discolored your fireplace glass is, it’s fast, easy, and inexpensive to remove the soot. All you need is some water, regular household vinegar, a bucket and a strainer! In just a few minutes, your dirty glass will be restored to its original, glamorous luster and sparkle.
Get Your Air Mixer Professionally Installed
Propane gas is highly volatile! As with any kind of installation that involves gas, you should have your new air mixer installed by a trained professional. When looking for a trained professional, it’s a good idea to choose one with an NFI (National Fireplace Institute) certification. An NFI-certified installer has received the proper training in gas hearth appliances and passed NFI’s rigorous exam, ensuring they meet high standards for safety and proper installation.