Is Paint Thinner Flammable? (Answered)

Paint thinner is a valuable substance that can bring the best out of your paint, especially if it’s been lying around for some time or if you want to use it in a sprayer by thinning out the paint.

It is specifically utilized to clean splashed paint or clean paintbrushes. But is paint thinner flammable?

According to OSHA, paint thinner is flammable. In other words, as it is combustible and possesses a flashpoint of around 199.4 degrees Fahrenheit (93 degrees Celsius), you can see it as a flammable substance.

To be precise, its flashpoint should be within 104 degrees Fahrenheit. We will come back to that.

What Do the OSHA & NFPA Say About Flammable Materials?

According to OSHA and NFPA, the flammability of any material depends on its flash point and boiling point. Therefore, these agencies use this material’s flashpoint and boiling point to categorize chemicals into flammable and combustible substances.

Through the Safety Data Sheet (SDS) of used flammable paint thinners, you will be able to see it as a Category 3 flammable material based on the OSHA standard. In other words, it has a flashpoint of about 73.4 to 140 degrees F, which is the same as 23 to 60 degrees Celsius.

One safety cabinet may have over 60 gallons of paint thinner, while a single storage location can house three safety cabinets. So, going by the above, can we say paint thinner is flammable?

Let’s find out!

Is Paint Thinner Flammable?

Also known as mineral spirits, paint thinner is a flammable material or chemical that should be stored as such. However, we have different technical definitions of how flammable liquids are, which determines whether they will burn quickly or not.

A paint thinner can somewhat easily catch on fire. This is per the Standard 29 CFR 1910.106 of the Occupational Safety & Health Association (OSHA). It states that a substance can be considered flammable as long as its flashpoint is around or below 199.4 degrees Fahrenheit (93 degrees Celsius).

But, if it is over 199.4 degrees Fahrenheit, it can be considered non-flammable. However, non-flammable substances can still catch fire at higher temperatures.

What Is the Flashpoint of Paint Thinner?

For the benefit of those that don’t know what a flashpoint means, the flashpoint is the temperature at which a substance emits vapors that is strong enough to catch fire when it comes in contact with an ignition source.

But what is the flashpoint of paint thinner? The flashpoint of paint thinner is typically around 40 degrees Celsius or 104 degrees Fahrenheit. Its flashpoint is a little hotter than the average healthy human being (98.6 degrees Fahrenheit).

However, it doesn’t tell the entire story, as specific ranges of flashpoints run from 73.4 to 140 degrees Fahrenheit, equal to 23 to 60 degrees Fahrenheit, making it hazardous, as it mustn’t be that hot before it can be prone to fire.

As much as there is a spark or flame, it will combust.

Can Paint Thinner Spontaneously Catch Fire?

Mineral spirits (paint thinner) can spontaneously catch fire, especially if their auto-ignition temperature reaches 745 degrees Fahrenheit, equal to 245 degrees Celsius.

In other words, it can combust even without any source of spark or ignition. Therefore, you must be careful with its handling and storage.

Can Paint Thinner Easily Catch on Fire?

Even though paint thinner is not considered a highly flammable liquid by the Occupational Safety & Health Association (OSHA) standards, it can easily catch on fire.

Therefore, we advise you not to take it closer to any ignition source or smoke.

Does Paint Thinner Have a Flammable Fume?

Yes, paint thinner has a flammable fume. It will not only combust but can also flame up. The fume is the only part that is explosive in paint thinner. So whenever you see a liquid burning, it doesn’t mean it is the actual liquid burning.

Liquids emit fumes (gas) at various temperatures based on the liquid type. The fumes are what combust. In other words, you should be more careful with the fumes as a fire risk when working with paint thinner, by working outdoors or in a well-ventilated area.

Is Paint Thinner Flammable When Dry?

In a nutshell, the dryness of a paint thinner means it has disappeared into thin air, meaning paint thinner is no longer available.

Therefore, it cannot be said to be flammable, as it is impossible to burn what does not exist. However, you have to note that the fumes may still hover around the air in poorly ventilated rooms instead of spreading out and fading off.

It is still highly flammable in such a condition (gaseous state), which explains why you must often work with paint thinners in good ventilated areas.

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