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As far as chemical reactions go, none are quite as
altogether beautiful, useful, and dangerous as fire.
Fires require three things to come together: a fuel source, heat, and oxygen.
While you’re probably familiar with most things that can catch fire, like wood or gas,
there are some everyday materials with unexpectedly fiery properties.
And since a lot of them are found in our homes,
knowing about them might even keep you safe!
So here’s 5 weirdly flammable things.
To create fire, you need a lot of heat to gain enough kinetic energy for molecules
from the fuel source to break their interactions and transition to the gas phase.
Those molecules can then react with oxygen in the
surrounding air in a process called oxidation.
The oxidation process then releases even more heat, which helps free more
molecules from the fuel to react with oxygen in a
self-sustaining chain reaction we call fire.
The heat and light released from that process make up the familiar,
visible flames we see in burning objects.
The minimum temperature at which all this can happen is called the flash point.
And different materials have different flash points.
Anything that has a flash point of 37.8°C degrees
Celcius and upwards is considered “combustible,” such as wood and paper.
That’s because they take some work to light on fire
since their flash point is way above room temperature.
On the other hand, things with flash points closer to room temperature,
like alcohols, are called “flammable.”
Because they can evaporate quickly and their fumes can catch fire.
So, in general, the lower the flash point, the
more easily something can be set on fire.
And something that can catch fire easily, although it has a pretty
high flash point, is plain ol’ flour like the kind used to make bread.
While it seems simple and harmless, as far as cooking ingredients go,
in the right circumstances, flour is pretty explosive.
The main component of flour is starch, which is a carbohydrate.
The molecules in a carbohydrate contain lots of energetic bonds
between atoms of carbon and hydrogen.
Oxidation can release the energy in those bonds, making them easy to burn.
When it’s all lumped together in a pile, flour isn’t especially likely to catch fire,
but when it’s dispersed in the air, like a cloud of dust, that’s a whole different story.
That’s because the individual grains of flour are small,
giving them a high surface area relative to their size.
So when they’re suspended in the air, they have access to lots of oxygen
surrounding them, making it even easier to burn.
What’s more, because those grains are so small, they burn up really fast and light
up nearby grains in the process, spreading the fire way
quicker than it would in a single, lumpy fuel source.
So if a spark or nearby flame catches part of a floury dust cloud,
it can set the whole thing alight!
In 2015, that exact scenario happened at a water park in Northern Taiwan.
A celebration involving bursts of colored corn flour turned into a
fireball that injured hundreds of people.
Thankfully, most cooking recipes that include flour involve getting it wet with water,
making it much less dangerous in the kitchen.
But even so, it pays to be careful when throwing bags of
flour around any flames, like a stove!
The same goes for other powdery foods like powdered coffee creamers too.
And fire risks aren’t limited to the stuff in the kitchen, either.
Many nail polish removers, and other household stain removers,
contain a key ingredient: acetone.
Acetone is great at dissolving things like nail polish and can be easily
washed away with water.
That combination naturally makes it great at removing stains,
but unfortunately, acetone, as you’ve probably guessed, has another property:
it’s really flammable!
Its flash point is at -18°C, making it easy to set alight.
And like flour, its molecules have similar carbon-hydrogen
bonds that release lots of energy during oxidation.
Finally, acetone molecules don’t interact as strongly with each other in
liquid form, so they have a tendency to evaporate from the surface.
In other words, it's pretty “volatile.”
That’s why nail polish remover has such a strong and distinct smell,
since the acetone floats easily into the air as a vapor.
And as we saw for flour, when small, tiny bits of material float around,
it makes them much easier to set on fire.
In fact, people have gotten seriously hurt applying nail polish remover near open
sources of flames like candles, since acetone vapor can set alight very quickly.
So if you’re going to use nail polish remover on a quiet night in,
safety officials recommend you don’t have any candles nearby.
In other cases, certain materials themselves might not be
combustible or flammable, but can still cause a fire.
Glass doesn’t burn very well at all.
But it can still turn into a secret arsonist, under the right conditions.
This time the culprit is the physics of glass, rather than its chemistry.
When light interacts with a dense but transparent material,
like glass, it effectively gets slowed down.
And because of that, if a ray of light approaches that material at an angle to its
surface, the path of that ray is also bent away from
the surface as it travels through it.
Physicists describe this as Snell’s law.
So, if you have a curved piece of glass, like a lens,
it can focus lots of incoming rays of light to a small spot called a focal point.
That’s how magnifying glasses work, using Snell’s law.
The light comes from a wide field of view, but narrows down to a
spot where we can see it all if we align it with our eyes.
Magnifying glasses can also focus a distant, bright light source like the sun to a
spot where a lot of the heat and light gets concentrated to a single point.
And much like a lens, curved pieces of glass-like snow globes, flower vases,
mirrors, and even some windows can produce a similar kind of effect.
It can also just so happen that a combustible or flammable material might happen
to align with the effective focal point of that glass, and be set on fire.
Fires have been caused by objects like mirrors sitting
near window sills in people’s homes.
On a large scale, the effect can be even more dramatic.
In 2013, a curvy building in London made of glass melted
part of a car on a nearby street as it reflected the sun’s rays!
Which happened for around two hours a day,
so the building had to be retrofitted with sunshades so it could stop melting things.
So it might be a good idea to keep crystal flower vases,
bottles of water, and mirrors away from the windowsill.
So far, we’ve talked about things catching fire when
they receive heat from some other source.
But there are strange instances where the fuel itself can
generate enough heat to basically set itself on fire.
Linseed oil is made from flax seeds, and it’s often used
on wooden furniture to protect it and make grain patterns in the wood more visible.
At first, it might not be all that surprising that linseed
oil can catch fire, since, well, lots of oils can be burned.
But in the right conditions, linseed oil can basically
set itself on fire because of the way it dries.
Most liquids dry by evaporating off water or some other
solvent in the mixture, and leaving the rest behind.
But linseed oil dries through oxidation, basically the
same process through which you create fire.
That doesn’t mean that it bursts into flames immediately
since there’s normally not enough heat to make the reaction self-sustaining.
But, as linseed oil dries through oxidation, it generates heat,
and if it gets hot enough, it can set itself on fire.
That’s especially problematic since people apply
linseed oil to furniture by rubbing it in with pieces of cloth.
And then when they’re done with the cloths, they often throw them into a pile.
As the oil in the pile of cloth dries, the cloths heat up,
and their collective heat can increase until the oil and cloths catch fire.
In 2014, a pile of linseed-soaked cloths was
identified as the source of a fire in a home in Maryland.
In fact, in 1991, a whole high-rise tower in Philadelphia
caught on fire for the same reason.
So if you do use linseed oil to spruce up the furniture,
safety officials recommend you wash the rags you use
and hang them out where there’s lots of airflow before storing.
Finally, there’s an object that really doesn't seem like it
should be flammable but burns incredibly easily: ping pong balls!
Specifically, older ping pong balls are surprisingly flammable.
A few people have noticed this and speculated that it’s because there was a gas
put into the balls during the manufacturing process that burns really well,
but, to be clear, it’s just ordinary air in there.
It’s the actual material of the balls, which is called celluloid, that burns really well.
Until about 2020, ping pong balls were still being made
of that stuff since it’s a light and durable plastic that
gave the balls the right properties for being whacked about.
Although it has a high flash point of over 175°C,
once celluloid hits that point, it can start burning without
needing a spark or flame to get started, and it burns really easily.
Celluloid gets its ignitable properties from a substance called nitrocellulose,
which was used as a replacement for gunpowder in weapons during the 1800s.
By the middle of the century, American entrepreneurs discovered that
dipping nitrocellulose in wax turned it into a hard, enduring substance,
and patented it as celluloid. Which was one of the first manufactured plastics.
Celluloid enjoyed a long stint in lots of applications,
famously including rolls of film like the kind used in projectors.
Unfortunately, when the lamp in the projectors got hot,
they had the tendency to make the celluloid film dramatically burst into flames.
Because of its flammable tendencies, celluloid fell out of use in most cases,
though ping pong balls were the exception until 2014, when they started to be
phased out because of the fire risks of transporting lots of balls around.
But older ping pong balls are still made of celluloid,
so you probably want to keep them away from any sources of flame.
And celluloid hasn’t totally disappeared either.
It’s still used to make, amongst other things, guitar picks!
But thankfully, as far as we know, there haven’t been any
unintentional fires caused by guitar picks, so for now, there’s nothing to fret about.
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