Glass is an interesting material. It can be used to make a variety of different products, including some that are very functional and others that are purely decorative.
Adding glass stones or marbles to a fire pit or backyard fire features has become more popular in recent years for their ability to retain heat and even add a little bit of décor.
Since adding glass to fire pits has become more popular in the last few years, I’ve become interested in exploring this new aesthetic…it’s sort of a primal meet future vibe. Here are some of the things I’ve learned.
What Type Of Glass Is Best For A Fire Pit?
In general, fire pit glass is made from one of two types of glass: Borosilicate or tempered. Though some companies are experimenting with blends and composites.
Borosilicate
Borosilicate is a type of glass that has been heat-strengthened through the process of thermal tempering. It’s chemically similar to a standard window pane, but it holds up better under extreme temperatures and can withstand more pressure than traditional window panes.
Tempered Glass
The tempered glass looks very much like any other sheet of tempered glass…it shatters into tiny pebble-like pieces when it breaks. Firepit glass is tempered, but unlike your car window or tabletop, the fire caustic chemicals can cause a chemical reaction that makes this type of glass even stronger and harder to break.
Composite Glass
Some manufacturers have started combining borosilicate with other types of glass in order to make their fire pit glass more affordable.
The biggest advantage is that it can be made using standard flat glass production methods, so the costs are very low…but don’t expect it to stand up as well under extreme temperatures or pressure. It’s also not likely to hold heat quite as long either. When you ask for borosilicate glass, you should expect to pay a bit more.
Is Fire Pit Glass Safe?
Firepit glass is safe since it is made from materials such as borosilicate and tempered glass. These materials are treated so that they can withstand high amounts of direct heat.
There are exceptions to everything…so always use caution when working with any materials that go in a fire pit. Here are a few precautions you can take or be mindful of:
- Make sure that any air holes in your fire pit or gas burners (if using a propane model) aren’t blocked by any glass or particulates.
- Make sure your fire pit glass is made from borosilicate or tempered glass and that the manufacturer recommends using this type of glass for fire pits.
- Keep a garden hose and bucket of water nearby in case something does go wrong.
Do Fire Pit Glass Stones Retain Heat?
Borosilicate and tempered glass stones will retain heat for a short time after the fire has been extinguished. The thicker and multilayered glass will usually retain heat longer than smaller pieces.
Firepit glass that is set against a brick or concrete base can be heated more quickly and retain the heat for longer periods of time than other types of fire glass materials.
Typically, fire pit glass will only retain heat for a few hours but to maximize the amount of heat retained in your fire pit glass, you should look for thicker pieces that are multilayered.
Can Fire Pit Glass Explode?
If you have used borosilicate or tempered glass, your chances are very small but it does happen from time to time. Small anomalies can lead to micro-fractures that lower the integrity of the glass and allow a small amount of water in. When the water heats up it can cause popping and cracking.
You need to use a little extra caution when using a fire pit with a cover over since these can be slightly more likely to cause glass explosions. This is because the glass can be heated by infrared radiation and quickly expand when exposed to oxygen in the air.
Having glass stones explode is extremely rare, so please don’t let any of that scare you out of picking some up. Like anything dealing with fire, it’s always a good idea to know some of the risks and how to handle or prevent them.
Can You Mix Fire Glass And Lava Rock?
Since both fire glass and lava rocks are capable of being used in fire pits you can freely mix them together. A popular technique is to use lava rocks for the base and fire glass as an accent.
Since lava rock can be thicker, it absorbs heat better than most stones which makes them a good choice underneath your borosilicate or tempered glass since this will help retain some of that heat throughout the night…although not quite as much as if you used a solid block of brick or concrete.
Why Is My Fire Pit Glass Turning Black?
Typically, fire pit glass will start to discolor or turn black due to the build-up of ash and soot. This is a standard byproduct of debris falling into your fire pit and the more you use it, the more buildup will occur.
If this discoloration isn’t cleaned up regularly, it can accumulate in the glass which could lead to damage over time since ash doesn’t burn completely. You should clean out your fire pit with soap and water at least once a year.
If you notice this discoloration doesn’t seem to be coming off, then it’s time for some stronger measures…you can try using an ash cleaning brush or sandpaper to get the job done.
There are also products on the market that can help reduce buildup and make your fire glass easier to clean in between uses.
If none of that works, you can always consider getting new fire pit glass stones to replace the old ones…you may want to change them out seasonally anyways, to match holidays or certain events.
Can You Use Glass Stones In A Wood Burning Fire Pit?
Fire glass is usually only meant to be used in metal fire pits or multi-fuel burners. You can use them on top of your wood-burning fireplace but you shouldn’t let the glass touch the logs.
Wood burning fire pits burn hotter than gas fire pits, so if the glass is allowed to touch the wood it could cause cracking or imperfections.
Glass stones are mainly designed to be used in gas-burning fire pits since they don’t burn as hot and put off less soot, keeping the stones cleaner for longer. But if you do want to use them in a wood-burning model, put a fire grate over the logs so that the glass stones have a flat, elevated area to lay on.
How Long Does Fire Glass Last?
On average, fire glass will last between 4 and 8 years. Factors such as the type and quality of materials used can raise or lower than average. If you’re using borosilicate or tempered fire pit glass then you’ll get the most bang for your buck since it’s designed with heat resistance in mind.
One thing that can affect how long your fire pit lasts is the quality of the stones you use. Some manufacturers include a lot more filler than others and since these won’t hold up as well against heat, they’ll need to be replaced sooner.
Regularly cleaning your fire pit will help keep your fire stones pristine and shiny. Even gas-burning fire pits will create small amounts of soot that can layer onto firestone, tarnishing them or turning them black.
It’s important to make sure your fire pit glass has been tempered or borosilicate (or both) so that you can get the longest lifespan possible.
Of course, if you’re using fire glass as a decorative accent and have it in place for just a few days at a time then it’s really not much of an issue. You should check the stones over to see how they look or smell after use but other than that, there is no real upkeep required which makes them easy to maintain.
Final Thoughts
Fire glass is a great alternative to traditional lava or pebble rocks that you would normally find in fire pits and it’s becoming more popular for lending an upscale look while still remaining affordable.
Firepit glass can be used alone, mixed with other stones like onyx, marble, or granite…or even combined with decorative accents like crystals or gems.
Since fire glass is transparent, you can use it with bright-colored flames to create an interesting effect that’s sure to grab attention from your guests or passersby. For example, blue flames against green stones would make for a fun psychedelic combination!
A recurring theme in this article is to use borosilicate or tempered fire pit glass since they’re designed to withstand the high temperatures that come with fire pits!