Can You Burn Glass? Facts & FAQ
You can burn nearly anything with a hot enough flame, but glass is one notable exception. Glass won’t burn in a fire because it’s created by combining, heating, and shaping silicon oxide. When superheated, silicon oxide melts into the transparent and useful material we know as glass. Glass can’t burn because it can’t oxidize, which is an essential part of fire. Glass exposed to fire may sometimes appear damaged, but other times it will shatter.
We know that some of you are probably grumbling that glass can melt if exposed to extremely hot flames, but that isn’t technically burning, because that requires oxidation. Glass has a melting point between 2,700 degrees Fahrenheit and 3,100 degrees Fahrenheit, while your average bonfire has a core temperature of about 1,500–1,650 degrees Fahrenheit. This is also the approximate temperature range of most house fires, meaning neither a bonfire nor even a house fire will come close to melting glass.
It’s important to note that this melting point is when glass becomes fully liquid. If heat is concentrated in one area of the glass, it will crack and shatter because the rest of the glass didn’t heat evenly. At temperatures approaching the melting point, you may notice some droplets of molten glass while the glass is heating up. Once the entire piece of glass reaches the melting point, it will be a fully molten liquid.
How Do You Melt Glass?
Glass is most commonly melted in a kiln, but it can also be melted with MAPP, acetylene, oxy-acetylene, and hydrogen torches. In a pinch, propane torches might work too. Whether you use a torch or a kiln to melt glass affects what you can do with it.
Lampworking is when you heat glass with a torch and manipulate it into the desired shape with special tools. Kilns, on the other hand, are a less dangerous way of melting glass – just pop it in the oven. You can then fuse or slump the molten glass by pouring it into a specialized glass mold. Glass kilns can also be used to bake pottery projects, though specialized kilns for both pottery and glass are available.
Is Heating Glass Safe?
While you can’t burn glass, heating and melting glass is perfectly safe as long as you have the right equipment and take the proper safety precautions. Molten glass is easily hot enough to cause serious harm to you or fragile objects, so you should wear safety goggles and heat-resistant gloves to protect your skin. Wearing long sleeves is also highly recommended, despite the high temperatures involved.
A mask is also essential. Glass is largely made of silicon oxide, and melting it releases a number of toxic gasses and chemicals. Dirty glass has the potential to be even more hazardous, depending on the contaminant.
Is It Safe to Put Glass in a Fire?
Yes, glass is pretty safe to put in a fire. It’s chemically inert and won’t emit toxic gasses when combined with other chemicals, and it won’t burn either. In the worst-case scenario, the glass might soften or even break, but it’s nearly impossible for typical flames to harm glass. There are many better ways to reuse glass than simply chucking it in a fire, though, because it will still be there after the fire dies down.
How to Safely Dispose of Glass
Since you can’t burn glass, how are you supposed to safely dispose of it? It depends on whether it’s broken or not. Intact glass, like whole glass bottles, can often be recycled. If you’re talking about broken shards of glass, they should be put into a cardboard box and thrown into the trash. Wrapping it in paper also works if you happen to not have any boxes.
Glass can’t burn in an average fire, but it can melt or shatter when exposed to hot enough temperatures. This is hard to do without the use of a kiln or torch, with few other heat sources providing enough heat to do anything to the glass.
Featured Image Credit: David Pineda Svenske, Shutterstock