Are You a Chemist? This article is to inform you of all the reasons you do not want to use gasoline in traffic marking paint!

I have been in the traffic paint business since 1976. I consider that the beginning of time for me! If you use any chemical or solvent to reduce your paint, make sure it is the one recommended by the paint manufacturer. In the last fifty years I have never come across a label that endorses diluting with gasoline. In fact, it is just the opposite, and here is why.

It Voids Your Warranty

First off, it voids your warranty! Should you have any issue with your application, and you have to answer “yes” to “Did you add gas to the paint?”, you are on your own. If that is not enough of a reason, let’s examine some of the not-so-good outcomes.

What’s Really in Gasoline

Impurities in gasoline can affect the adhesion of the paint. Refiners use additive packages designed for combustion engine performance, not coatings. These include additives like ethanol, which raises octane. Alcohol may be an ingredient in some waterborne coatings, but it rarely belongs in solvent-borne coatings (alkyds). I won’t go into a full list of the paint contaminants in gas. If you want to play chemist, you can research them on your own.

Years ago, when we had leaded gas and leaded pigments (like chrome yellow), you could argue that gasoline improved your drying time. It could also change the color of the coating, usually turning a bright yellow toward orange. That is one way a field technician can tell you used gasoline.

The Finger Test

Here is a test. I do not recommend it, because gasoline contains benzene and other chemicals that absorb through your skin. However, it demonstrates the purity of solvents like toluol, xylol, or MEK. If you put a little gasoline between your forefinger and thumb and rub, you will feel a slippery, oily film as it evaporates. That film is the heavier fractions and additives left behind. Now do the same with a solvent recommended by a reputable manufacturer. It will feel clean and dry, because a pure solvent evaporates completely and leaves nothing behind. Whatever stays on your fingers also stays in your paint film.

Safety

Some contractors not only dilute with gas, but they don’t use an approved safety container. This is dangerous and illegal in most jurisdictions. And keep in mind:

Fire and explosion hazard. Gasoline’s flash point is around −45°F, so its vapors can ignite from sparks, hot engines, or striping equipment at almost any temperature. Recommended thinners have higher, controlled flash points.

Static ignition risk. Pumping or agitating gasoline-thinned paint through airless or pressurized systems can build static and ignite the vapors.

Worker health exposure. Spraying gasoline atomizes benzene, a known carcinogen, right into your crew’s breathing zone.

So, Let’s Ask the AI

In the age of AI, I asked Claude, an AI assistant, for a list of reasons. Here is what it came back with.

Paint Performance

Incompatible with waterborne paint. Gasoline won’t mix with water-based traffic paint. It separates, curdles, or coagulates the batch and ruins it.

Damages the resin system. In solvent-based paint, gasoline’s aromatics and additives can attack or destabilize the binder, which weakens film strength and adhesion.

Poor or uneven drying. Gasoline evaporates at a different rate than the formulated solvent blend. You can get surface skinning with soft paint underneath, tackiness, or slow no-track times.

Bead retention problems. A weakened or over-thinned film doesn’t embed and hold glass beads properly, so retroreflectivity drops quickly.

Reduced durability. Expect faster wear, chipping, and fading, which means earlier restriping.

Wrong film thickness. Over-thinning cuts mil thickness and hiding power below specs.

Can bleed or soften asphalt. Gasoline is a petroleum solvent that can soften fresh asphalt or sealcoat and cause bleed-through or discoloration.

Equipment

Now let’s look at some potential equipment issues:

Attacks seals, hoses, and gaskets that aren’t rated for gasoline, causing leaks and pump failures.

Leaves gum and varnish deposits from fuel additives that clog filters, tips, and guns.

Legal and Liability

Lastly, there are some legal issues that may affect your application:

Voids warranties. Manufacturers won’t stand behind paint altered with unapproved thinners.

Violates specs. DOT, municipal, and commercial jobs specify the product as formulated. Adulterating it can fail inspection or breach the contract.

VOC and air-quality violations. Adding gasoline raises VOC content above regulatory limits in many states and air districts. Benzene is also a hazardous air pollutant.

OSHA and insurance exposure. Using fuel as a thinner contradicts the SDS and safe-use guidance, which creates liability if there’s a fire, injury, or failed job.

Hazardous waste issues. Contaminated leftover paint and cleanup material become harder and more expensive to dispose of.

Remember, do not use solvents in waterborne coatings unless the manufacturer specifically recommends it.

Why Would Anyone Do It?

I can only think of two reasons you would consider using gasoline, and neither is acceptable!

The first is cost. Gasoline is cheaper than the recommended solvents. But that doesn’t hold water. Even if gasoline didn’t have its plethora of negatives, you would need less of the recommended solvent, because it “cuts” the paint rather than just “diluting” it.

The second is convenience. If you are a serious, professional contractor, you plan ahead and purchase the correct solvent at the same time you purchase your paint.

In Conclusion

Think ahead, follow the manufacturer’s guidelines and all applicable laws, and leave the gasoline in your fuel tank and your approved safety can!