Mineral oil is a catch-all term for a group of light, colorless and odorless mineral oils that are extracted from petroleum. “Mineral” is meant to distinguish the oil from “vegetable” oil. Most people will have some mineral oil laying around their homes in one of its different forms. But are they storing a dangerously flammable liquid or is mineral oil completely safe?
Mineral oil can catch fire fairly easily, but is not technically a flammable liquid, according to OSHA standards. It has a flashpoint around 335 degrees Fahrenheit (168 Celsius), which does not qualify as flammable, even though it certainly can catch fire.
Some of the flammable distinctions seem arbitrary and can be misleading. Lets take a closed look at what mineral oil is and the fire hazards that it can present. Take a look.
Also read: What Makes Something Flammable?
Table of Contents
What Is Mineral Oil?
Mineral oil is an oil made from petroleum byproducts. The name mineral is not, technically, accurate – minerals are specific chemicals trapped in rock, but it does a good job of distinguishing this type of oil from more organic vegetable oils used in cooking.
The most common mineral oil is paraffin, oil but there are others such as alabaster polish and light mineral oil (used in the process of sharpening tools or as an anti-rust coating).
Mineral oil can also be used as a fuel in some machines, it can be used as brake fluid, and for the liquid submersion cooling of electronic components (particularly in high-performance computing).
There are also more complex technical uses for mineral oils such as in X-ray crystallography and in particle physics – we won’t go into the precise details of these uses here, mostly because I don’t fully understand them myself.
One really unusual use for mineral oil is to clean freshly produced poker chips – it is used to remove any residue from the manufacturing process.
Interestingly, mineral oils are considered to be mainly non-toxic and there is no evidence of any harmful effects due to short-term exposure and the World Health Organization (WHO) does not find any evidence that these oils are carcinogenic either.
Can It Catch Fire?
Yes, mineral oil can catch fire. In fact, this is a property that makes it useful both as a fuel and as a source of entertainment.
When you go to watch fire breathers, they will use paraffin to get the fire breathing effect and that’s because mineral oil has a relatively low burning temperature.
This video shows some fire breathing with mineral oil (I do not recommend anyone try this, it is very dangerous):
However, it’s worth noting that this doesn’t mean that mineral oil is “flammable”. The flashpoint temperature is still higher than 199.4 degrees Fahrenheit (93 Celsius). This flammability standard is defined by OSHA, here.
Flashpoint is the temperature at which a liquid gives off enough vapors (fumes) to ignite in the presence of a spark or flame.
Also read: Is Vegetable Oil Flammable? Technically No…
What Is The Flashpoint?
The flashpoint of mineral oil, that is the temperature at which it will ignite in the presence of a naked flame or spark is around 335 degrees Fahrenheit (168 Celsius).
This means that as long as you take sensible precautions when storing mineral oil, it doesn’t represent a huge fire hazard. You need to ensure that it’s kept in a ventilated area to prevent fumes from building up and that the storage containers are properly sealed and free of leaks.
At What Temperature Does It Burn?
As there are several different types of mineral oil, there is no conclusive answer to this and if the answer is important to your usage – you should always consult a manufacturer’s safety sheet to get the exact temperature for mineral oil combustion. However, we can provide some rules of thumb.
What is the Boiling Point?
Again, there will be a fair amount of variation in the boiling points of different mineral oils, but the atmospheric boiling point is around 650 degrees Fahrenheit.
That is, mineral oil boils at a temperature higher than the flashpoint.
It’s worth noting that the autoignition temperature of mineral oil is higher still at around 690 degrees Fahrenheit.
Can It Spontaneously Combust?
Mineral oil auto-ignites at 690 degrees. So, it can spontaneously ignite if it is somehow heated to that temperature.
Under normal circumstances there is no way for mineral oil to reach these temperatures – for example, direct sunlight doesn’t have anything like the energy to raise the temperature up to this point.
That doesn’t mean that mineral oil won’t catch fire in a bigger blaze, but that’s not “spontaneous combustion” that’s exposure to heat and flame, or standard combustion.
Is Baby Oil Flammable?
No. Baby oil, is another form of mineral oil, and it too has a flashpoint of 335 degrees Fahrenheit which is not technically flammable, but still catches fire quite easily.
Take a look at this video to see how easily baby oil can catch fire:
However, it is possible to catch baby oil on fire when it is used in the presence of a naked flame (and, in fact, you can even make a candle out of baby oil, if you want to – baby oil will definitely burn).
Is Mineral Oil Toxic?
Mineral oil is not toxic in small doses, but we would note that while we wouldn’t expect you to burst into flames from drinking it – you should still avoid doing so.
Why? Because mineral oil is a natural laxative and the results of drinking it can be rather unpleasant, particularly if you’re not expecting them.
Remember Fire Breathing Requires Training
Finally, a warning.
Mineral oil can be used in fire breathing, but please, please don’t try to learn fire breathing at home.
This is a skilled discipline and done wrongly you could end up with serious burns or even set your home or environment on fire. This isn’t the sort of thing you should learn from a YouTube video.