So, Is Cornstarch Flammable?

Everyone knows that house fires are incredibly dangerous and, regrettably, all too common. Most house fires start in or near the kitchen, so if you want to avoid your house going up in flames, it pays to become more fire-aware concerning the materials you have in the kitchen.

lighting cornstarch with lighter
Cornstarch will ignite but not that fast when in compact form, as you can see.

Sometimes the most innocuous and innocent goods can be serious fire hazards! How about cornstarch? Is it flammable?

Yes, cornstarch is highly flammable as long as it’s dry. It will readily ignite and burn hot and quickly, and it’s a special hazard if it is hanging in the air as dust where it can combust with deadly effect.

Cornstarch is one of those things that most of us reach for and use so often it hardly bears a second thought. But believe it or not, it has caused some serious disasters over the years, starting fires responsible for many deaths.

You don’t need to throw the stuff in the garbage just yet, but it is in your best interest to brush up on just what kind of fire hazard cornstarch really is. Keep reading and I’ll tell you all about it…

Is Cornstarch Combustible?

Yes, it is; cornstarch is not only flammable but also combustible. The catch here lies in the form it takes. When it’s in a compact, solid state, it poses little to no fire hazard.

However, when it’s in a finely ground “dust” form such and suspended in the air, it can ignite rapidly and destructively. The reason being that the smaller surface area to volume of the cornstarch particles allows for a faster reaction with oxygen in the air.

This phenomenon is a well-documented industrial hazard, and potentially might happen at home in rare cases.

Does Cornstarch Ignite at Any Temperature?

Yes, cornstarch can indeed ignite at various temperatures, especially when it’s dry.  It’s important to note that cornstarch doesn’t possess a specific flashpoint like other substances such as gasoline or alcohol.

Instead, it has an ignition temperature, which is the lowest temperature at which it can ignite in open air with a source of ignition. For cornstarch, this ignition temperature is around 356 degrees Fahrenheit.

The absence of a defined flash point is due to the fact that cornstarch doesn’t vaporize like liquids, and instead it ignites when enough heat energy is supplied to it.

Does Cornstarch React with High Temperatures?

Yes, cornstarch does react with high temperatures. In typical cooking scenarios, cornstarch may break down or toast, but it doesn’t react negatively in any way until it reaches its ignition point.

This is when the cornstarch particles suspended in the air can ignite and rapidly burn all at once. Know that if even a small amount of cornstarch reaches this point, the rest of it will likely follow suit instantly!

This reaction can be particularly dangerous because it happens so quickly and intensely, making it impossible to stop from combusting and hard to control once the fire starts.

Warning: Cornstarch Dust is a Major Fire Hazard!

Cornstarch dust, like many other types of dust, poses a significant fire hazard, especially when suspended in the air. If ignited, it can combust instantaneously, leading to severe consequences.

Cornstarch and other food “dust” have been held responsible for several serious and fatal accidents over the years.

For instance, in 2008, a sugar factory in Georgia experienced a devastating fire due to sugar dust, which, like cornstarch, is a combustible dust.

Although the conditions leading to such a severe reaction are unlikely to occur in a home setting, it’s not impossible, particularly when handling large quantities.

A spill with a large bag on a dry day could result in cornstarch dust suffusing the air, waiting for a single spark to ignite it combustible all at once…

As innocent as it seems, you should always take safety precautions when dealing with combustible materials like cornstarch in and around the kitchen.

While we experimented with a little bit of cornstarch inside a spoon and barely made it burn (see pic above), when in powder form, it ignites much quicker, as you can see:

Dust Explosion Using Corn Starch

Will Cornstarch Make a Fire Worse?

Yes, it will. When introduced to an existing flame, cornstarch’s properties allow it to burn at high temperatures and rapidly. As such, it can serve as fuel readily for any fire, increasing its intensity and duration.

While this reaction won’t last forever- cornstarch will burn itself out- the initial boost in heat and speed of the flames can worsen the fire and the severity of the incident you’re facing.

Keep cornstarch away from open flames or any source of ignition to prevent any potential fire hazards.

Is Cornstarch Reactive with Other Substances?

From a fire safety perspective, cornstarch doesn’t pose significant reactivity concerns when combined with other substances.

It can create fascinating effects, sure, especially when mixed with water; this forms what eggheads call a non-Newtonian fluid, a substance that behaves like a liquid when at rest but becomes solid under pressure. Neat!

However, even though these reactions are intriguing, they do not pose any notable hazards to people or property outside of its usual flammability.

The changes that occur are typically physical, not chemical, meaning the inherent properties of cornstarch remain much the same.

So at least there is no need for concern regarding potential dangers when cornstarch interacts with common substances elsewhere in your home.

How Should You Deal with Cornstarch Exposed to Fire?

Handling a cornstarch fire doesn’t require any special extinguishing agents. Standard firefighting measures, such as using water or common types of fire extinguishers, will put out a cornstarch fire easily enough.

If you’re facing a situation where a large amount of cornstarch is at risk of catching fire, you may wet down the cornstarch beforehand to prevent it from igniting providing you have enough time and it’s safe to do so. But do be extra careful to not knock a big quantity of the dust into the air!

If there’s a substantial amount of cornstarch dust in the air it could lead to instant and potentially deadly combustion!

In such cases, the best course of action is to evacuate the area immediately and call 911. Safety of you and yours must always be the top priority.

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