Silicone shouldn’t be mistaken for the element Silicon, though it does contain a little silicon. Over the last few years, it has become one of our “go-to plastics”, as it is very easy to use and has many different applications. It’s in everything from caulk to food storage vessels. But is silicone a fire hazard? Will it burn and if so, how much of a problem is this likely to be in your home?
Silicone is not considered to be flammable. It can catch fire and burn but requires high temperatures to do so. The ignition temperature of silicone is 842 degrees Fahrenheit (450 Celsius).
While it may not be a serious fire hazard, there are some things to be aware of when it comes to silicone. Let’s take a closer look at the properties of silicone.
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Also read: What Makes Something Flammable?
What Is Silicone?
Silicone (also called elastomers) is a form of plastic. It is made up of “siloxane” groups. There are many different forms of silicone, depending on how many siloxane groups are put together in a chain.
This can mean that they appear as a colorless oil (suitable for use as a lubricant, for example) or whether they have a rubber-like appearance and texture (such as the silicones used in kitchenware).
They may be used for a variety of different purposes from medicine to thermal insulation.
You probably have some around your home in the form of silicone rubber, silicone resin, or silicone caulk and you might even have silicone grease or silicone oil too.
Silicone is prized for its thermal stability. That is, it has the same properties over a wide range of temperatures. And this range is typically -148 Fahrenheit to 482 degrees Fahrenheit (-100 to 220 Celsius).
This means that it is not flammable. It is also a thermal insulator because it doesn’t conduct heat very well.
It is also an excellent electrical insulator and is not likely to be the cause of an electrical fire within your environment.
Finally, silicone is non-toxic, resistant to microbial growth, and waterproof and thus, it’s a very handy plastic to use in a wide variety of ways.
Also read: Is Epoxy Flammable? Yes and No…
Will It Catch Fire?
Yes, silicone will catch fire. This is true of nearly everything if you supply enough heat over a long enough period of time. However, silicone does not burn easily, and it burns at temperatures in excess of 482 degrees Fahrenheit (250 Celsius).
Generally speaking, it is unlikely to encounter these high temperatures in household or office use (unless there is already a fire), though it is possible to find temperatures like this in kitchens sometimes.
Silicone can be formulated to be used at even higher temperatures, if necessary, and it often is when silicone is used as an adhesive.
Interestingly, silicone does not melt nor does it sublimate (that is the process by which a solid become a gas without an intermediate liquid stage), but rather it remains solid until it ignites.
It’s worth noting that if you’re using silicone rubber – it may not catch fire until you reach a high temperature, but at around 390 degrees Fahrenheit (198 Celsius), it will start to deform and lose its pliability.
Also read: Is Glass Flammable?
Is It Fire Resistant?
Yes. Silicone is both heat and flame resistant.
Thanks to the unusual chemical properties of silicone as plastic – it doesn’t catch fire very easily and it doesn’t act as a conductor of heat, which means that it is fairly fire-resistant.
Take a look at this video for a flammability test comparing silicone to other plastics:
Is It Safe When Heated?
Yes, silicone is safe when heated. It wouldn’t be much use in kitchenware if it wasn’t.
While silicone can, at high temperatures, deform a little – it won’t melt or boil. Silicone is also chemically neutral and even if it burns, as you will see below, you don’t need to worry about the byproducts.
Also read: Is Rubber Highly Flammable?
What Happens If You Burn Silicone?
Assuming that you’re burning the silicone in the air (or oxygen), then the main byproduct of burning silicone is silicon dioxide (SiO2) “silica”, you know it as sand or glass in everyday life.
Silicon dioxide does have some health concerns.
It will also release some gasses.
In general terms, silicone is safe to burn and the byproducts are generally non-toxic. This is another good reason to use silicone when compared to some other plastics which can be frightfully toxic when they are on fire.
Does It Melt Or Burn?
Silicone does not melt. It can, under the right circumstances, burn.
What About Silicone Spray?
Yes, while silicone is not generally flammable, the one exception is when you aerosolize it. The tiny droplets of silicone are exposed to far more oxygen than silicone is in other applications and this makes the aerosol flammable.
See it in this video:
No, silicone caulk like most other silicone products is not flammable. However, you should be aware that there are many different types of caulk out there and they are not all silicone-based.
Some material caulks are flammable and you should always read the packaging carefully to be certain of what you are dealing with.
No, silicone sealant should not be flammable, unless it is being used in conjunction with another solvent-based, and thus flammable, sealant.
It is also worth noting that after curing, which takes up to 48 hours for silicone sealant, the end product is not flammable either.