Styrofoam and Gasoline – What Happens When Mixed?

What happens when styrofoam and gasoline are mixed? Is it safe to do that? Suppose you’re a naturally curious person who happens to ask these questions. In that case, this article will try to answer some misconceptions and questions about what gasoline does to Styrofoam.

If you put Styrofoam (extruded polystyrene) in gasoline, it can break down. The air inside Styrofoam escapes, which causes it to become a gelatinous and sticky substance. If you leave it alone to dry, it solidifies again. However, it’s not the same material as before, without the air. It becomes a material that closely resembles plastic.

Read on to learn more about mixing gasoline and Styrofoam.

Why Does Styrofoam Dissolve in Gasoline?

styrofoam in gasoline

What Is a Styrofoam?

Before we get to that question, we need to clear something up. Styrofoam is the brand name of DuPont’s insulation board.

Styropor vs. Styrofoam

You shouldn’t also mistake it for Styropor, an expanded polystyrene foam registered trademark of the German chemical giant BASF AG. In the construction industry, Styrofoam is known by the generic term extruded polystyrene foam or XPS.

Now, let’s go back to the question: Why does gasoline dissolve Styrofoam?

Polystyrene and Gasoline Share a Similar Structure

Styrofoam or polystyrene shares a similar molecular structure to that of gasoline.

According to an article published in Environmental Science & Technology, researchers found high polycyclic aromatic hydrocarbons (PAHs) in packaging materials made from polystyrene foam.

PAHs are a large class of organic compounds naturally occurring in coal, crude oil, and gasoline. They’re also present in certain types of food, such as meat, when you cook them in high heat.

Like Dissolves Like

What does this all mean? The primary chemical theory says that if two substances have similar molecular structures, they’ll typically dissolve in each other. This is why extruded polystyrene (Styrofoam) and different types of plastics degrade when mixed with gasoline.

When you put Styrofoam in gasoline, the hydrocarbons in both materials interact freely.

This causes the high-energy bonds in the aromatic chain to break in exchange for single covalent bonds to gain more stability.

A Combination of Gasoline and Polystyrene Results in a Slimy and Amorphous Solid

As a result, Styrofoam breaks down and releases trapped air. This chemical reaction forms a slimy and “amorphous solid” material. Amorphous solids can slowly flow like liquids but can also be rigid, such as glass and plastic.

That’s why they’re called pseudo-solids or super-cooled liquids. If you’ve ever tried dissolving Styrofoam in gasoline, you’ll notice it becomes gooey-like melted marshmallow or stringy-like melted mozzarella.

Is It Dangerous to Mix Gasoline and Styrofoam?

Even if you don’t mix them, gasoline and Styrofoam (or other things made of polystyrene) can be toxic and dangerous.

To give you a better idea, let’s talk about in greater detail the health and safety hazards of these two materials:

1. Effects on Health

Burning polystyrene, such as Styrofoam, releases big amounts of carbon monoxide, styrene, and other toxic chemicals. Short-term or long-term exposure to its poisonous fumes could cause various health problems.

What Happens If You Breathe in Polystyrene Fumes

Some of the symptoms that you might experience include:

  • Blood and kidney problems
  • Coughing
  • Depression
  • Dizziness
  • Fatigue
  • Headache
  • Increased nasal discharge
  • Irritation of the inner lining of your nose, throat, and lungs
  • Nausea
  • Poor muscle control (ataxia)
  • Vomiting
  • Weakness
  • Wheezing

To be clear, you’re only in trouble if you burn polystyrene (Styrofoam). It doesn’t only release styrene gas, but it also bonds with oxygen to form carbon monoxide, which is an odorless gas that’s responsible for thousands of deaths every year in the United States.

You don’t need to burn gasoline to experience adverse effects on your health. According to Medical News Today, adults exposed to 20 to 50 grams (0.7 to 1.8 ounces) of gasoline can suffer from severe intoxication.

And 350 grams (approximately 12 ounces) of gasoline is enough to kill a person who weighs 70 kilograms (about 154 pounds).

What Happens If You Breathe in Gasoline Fumes

Inhaling gasoline vapor can cause the following symptoms:

  • Dizziness
  • Fainting
  • Headache
  • Irritation of the eyes, throat, and nose
  • Nausea
  • Death (if you inhale incredibly high levels of gasoline)

2. May Result in a Homemade Torch or Firebomb

What happens when you combine two highly flammable materials? With the correct ratio, making a homemade torch or firebomb is possible, which is extremely dangerous if you put Styrofoam in gasoline.

What Is a Napalm

Napalm, also referred to as firebomb or firebomb fuel gel mixture is a jelly-like substance often used to make explosives. Once ignited, it can burn at around 5,000°F (2,760°C) or higher. That’s hot enough to melt anything made of iron alloy and steel.

You can imagine what will happen if it sticks to your skin. It can cause extremely severe burns.

How to Make Napalm

People make napalm by adding gasoline (in varying concentrations) to a gelling or thickening powder that consists of naphthalene and palmitate (thus, the name “napalm”), as well as other additives. Other earlier thickening agents include aluminum and soap flakes.

What Is Napalm-B

But some people think that the gasoline-Styrofoam mixture is more similar to that of Napalm-B, a napalm successor.

Napalm-B, also called super napalm and NP2 is made of 25% gasoline, 25% benzine (a colorless and flammable liquid mixture), and 50% polystyrene (which is what Styrofoam is). Others would use 33% gasoline, 21% benzene, and 46% polystyrene.

Warning: This is strictly for information only. Please don’t try making homemade napalm using gasoline and Styrofoam unless you don’t mind going to prison or hurting yourself and others.

Again, what happens when you put Styrofoam in gasoline? You’ll get a sticky and highly flammable material if you put styrofoam in gasoline. This is similar to Napalm, a homemade torch or firebomb, so do not attempt to make this at home.

Can You Use Styrofoam and Gasoline as a Roof Sealant?

styrofoam and gasoline as roof sealant

Average Cost of Sealing a Roof

HomeAdvisor says the average cost of sealing a roof is $1,262, or a total average of $0.65 to $5 for every square foot. It can go as high as $3,200 or more. So, it’s unsurprising that some people will look for a cheaper alternative.

This brings us to these questions: Can you use styrofoam and gasoline as roof sealant? Is it as effective and safe as commercial sealants?

There are few large-scale, peer-reviewed studies on the viability of Styrofoam and gasoline as an alternative sealants. However, I found an investigatory project titled “Styrofoam and Gasoline as Alternative Sealant” online.

The objective of the investigatory project was to develop an alternative to commercial sealants using gasoline and Styrofoam.

If successful, the next step was to compare it to commercial sealants based on the following criteria: the amount of time needed to dry, the ability to prevent water from passing through, and the quality of its adhesiveness.


The materials used for this project were the following:

  • 500 milliliters (roughly 16.9 ounces) of Special XCS gasoline
  • Small pieces of Styrofoam
  • Two containers
  • Two galvanized irons (4×4)
  • A commercial sealant


The procedure was simple. They just cut the Styrofoam into pieces and pour them into the 500ml gasoline. Then, they mixed the two until they became thick and sticky.

Commercial vs. Alternative Sealant Drying Time

It only took 5 to 10 minutes for the commercial sealant to dry, while the alternative sealant gasoline plus Styrofoam took 15 to 20 minutes to dry. Commercial liquid sealants will take around 8 to 24 hours to dry completely.

Both Formed an Effective Water-resistant Film

Both types of sealant formed an effective water-resistant film. Although the alternative sealant could stick to the roof, it may quickly lose its effectiveness if you keep removing it.

Alternative Sealant’s Flammability

The researchers concluded that mixing gasoline and Styrofoam can create a sealant. However, there’s still one thing that needs to be addressed by future researchers—the flammability of this alternative sealant.

Should You Use the Mixture of Gasoline and Styrofoam as a Roof Sealant?

But the real question is, should you use these two materials for the said purpose?

Definitely not! Remember: gasoline and Styrofoam are two of the key ingredients for making homemade firebombs. Once ignited, even by accident, it will burn your roof without stopping and could cause severe injury or even death.

Alternative Sealant May Easily Break Down Due to Harsh Weather Conditions

Even if it’s not flammable, the mix will likely not last very long. Sooner or later, it will break down due to constant exposure to harsh weather elements.

Commercial Roof Sealants Are Still Your Best Option

Overall, commercial roof sealants are still your best option. If money’s an issue, acrylic roof sealants are usually the cheapest at $0.15 to $0.75 for every square foot.

Ask Your Handyman for a Recommendations

If you’re having a tough time choosing the best sealant for your particular problem, ask for recommendations from an experienced roofer, handyman, or someone at the hardware store.

Get a Sealant with C5 ISO Certification If You Live in Area with Harsh Conditions

Sealants usually have ISO certification, which determines how well they’ll protect the surface of your roof from corrosive elements. C1 offers the least protection, while C5 provides the best protection.

If you live in harsh weather conditions, experts recommend looking into a sealant with a C5 ISO certification.

What Dissolves Styrofoam Other Than Gasoline?

styrofoam and gasoline reaction

Some of the gasoline alternatives on this list may or may not work in dissolving Styrofoam. I suggest you try different sizes and types of polystyrene products (disposable cups, bowls, plates, etc.)—not just Styrofoam—to get a good idea of how effective they are:

1. Pure Acetone

Colorless Liquid Widely Used in Plastic Production

Acetone, also called propanone, is a colorless liquid widely used in plastics production. It’s also found in solvent products, like denatured alcohol and nail polish remover.

A Cup of Acetone Can Dissolve Polystyrene

A small amount of acetone—let’s say, a cup—is enough to absorb a large amount of Styrofoam. If you want to see how fast it works, the Mad Scientist YouTube channel made a video about this.

Type “Dissolving Styrofoam With Acetone Experiment (Making Slime With Styrofoam And Acetone)” on the search box.

Non-polar Solvent Can Dissolve a Non-polar Styrofoam

According to the Department of Chemistry of The University of Utah, acetone is a non-polar solvent containing carbon-hydrogen bonds. Since Styrofoam is also non-polar, it will only dissolve in non-polar solvents.

Styrofoam doesn’t undergo a chemical change when you mix it with acetone. What happens is more of a physical change.

Softens the Styrofoam by Breaking Polystyrene Molecules’ Bonds

Acetone softens Styrofoam and breaks the bonds of polystyrene molecules, allowing the chains to flow past each other. This causes the trapped air in Styrofoam to escape, which in turn causes it to collapse.

2. Oils

With the right amount of time, some oils (e.g., canola oil, fish oil, and olive oil) can dissolve Styrofoam. Oils that are esterified are especially effective for this purpose.

Esterified means the substance has undergone the esterification process to form at least one ester compound, often used as a fragrance and flavoring.

Oils You Can Use to Dissolve Styrofoam

Certain essential oils can also be used as alternative Styrofoam solvents, including the following:

  • Bay (Laurus nobilis),
  • Eucalyptus (Eucalyptus radiate),
  • Lemon rinds (Citrus limon),
  • Rosemary (Rosmarinus officinalis), and
  • Thyme (Thymus vulgaris).

Essential oils produce a variety of volatile organic compounds (VOCs). Some of these VOCs contain volatile hydrocarbons, which, as you learned earlier, can help dissolve Styrofoam. While this is good, it also highlights the risks when ingesting essential oils.

3. Benzene

Colorless to Pale Yellow Liquid

Benzene is a liquid chemical (at room temperature) that smells sweet and is colorless to pale yellow. In some industries, it’s used to manufacture nylon, pesticides, plastic products, resins, and synthetic fibers.

Present in Many Products

It’s also present in many consumer products, such as adhesives, cleaning products, detergents, dyes, gasoline, lubricants, paint strippers, rubbers, and burned tobaccos.

Highly Flammable Liquid

Mohammad Samir, a Petrochemical Engineer, suggested on an online forum on ResearchGate to dissolve up to 68 grams of polystyrene in 100 millimeters of benzene. But be careful because benzene is a highly flammable chemical.

4. Xylene

Xylene is a colorless and sweet-smelling hydrocarbon. Like most chemicals included on this list, it can be dangerous because it’s flammable and toxic to humans. Some of its more eco-friendly and economical substitutes are carrot oil, pine oil, and rose oil.

Conclusion: Styrofoam and Gasoline – What Happens When Mixed?

The resulting product of mixing gasoline and Styrofoam is a gooey and sticky white substance. But if you leave it out to dry, the mixture will solidify and look similar to plastic.

Because of its explosive nature, I highly discourage you from combining the two to prevent harming yourself and other people and prevent property damage.