Why Add Gasoline When Painting?

[MirandaDella]

Because paint is a viscous oily pigment that is flammable when wet, insoluble in water, slightly soluble in fats, and soluble in alcohols, aldehydes, ethers, benzene, and alkanes, while being highly soluble in gasoline, kerosene, and diesel. Therefore, paint can be washed off with gasoline. Below is relevant information: Decorative Functions of Paint: Color, gloss, patterns, and smoothness. Applying paint to objects of different materials can result in vibrant and colorful appearances, playing a role in beautifying the human living environment and making a significant contribution to both material and spiritual life. Gasoline: Gasoline is a volatile, flammable hydrocarbon mixture liquid obtained from the distillation and cracking of petroleum, used as fuel. It appears as a transparent liquid, is combustible, with a distillation range of 30 to 220 degrees Celsius, and mainly consists of C5 to C12 aliphatic hydrocarbons and cycloalkanes.

[LeGraham]

Using gasoline to thin paint is actually an old practice. Gasoline can dissolve the resin in oil-based paint, making the paint thinner and easier to apply. Back in the day, experienced mechanics in repair shops often did this since gasoline was cheap and readily available. However, gasoline evaporates too quickly—before the paint even dries properly—leading to issues like bubbling and cracking in the coating. It can also corrode plastic parts. Nowadays, specialized thinners are used instead. For example, turpentine is used for alkyd paint, and lacquer thinner (banana oil) for nitrocellulose paint. These dry more evenly and don’t damage the car. Most importantly, they’re much safer—gasoline can ignite with just a spark. I witnessed a paint-mixing bucket catch fire when I was younger.

[StHector]

Adding gasoline to paint is quite risky. The reason gasoline can be used as a thinner is mainly because both gasoline and paint are organic compounds, which can dissolve each other, making the paint smoother to apply. However, the issue is that gasoline has a very low flash point—it can evaporate at temperatures as low as -20°C, filling the entire workshop with flammable vapors during spraying. When I worked at an auto repair shop, a worker tried to save money by using gasoline to thin paint. A spark from a grinder ignited the entire bucket of paint, nearly blowing up the paint booth. Nowadays, professional shops use dedicated thinners. Although they are more expensive, they are much safer and don’t have such a pungent odor.

[SanEmiliano]

The primary reason for using gasoline as a paint thinner lies in its solvency. The resin and pigments in paint are large molecules, and the alkanes in gasoline can break these molecular chains, making the paint thinner and easier to apply. However, this method has significant drawbacks. Firstly, it causes pollution—the benzene compounds released by gasoline evaporation are highly toxic, leading to dizziness with prolonged exposure. Secondly, it damages the paint film structure, causing it to powder and peel after drying. Lastly, it poses safety hazards; when the ventilation system is turned on during spraying, gasoline vapors can ignite upon contact with static sparks. Nowadays, eco-friendly water-based paints are used for automotive touch-ups, which can be diluted with water.

[DelLeah]

Using gasoline to thin paint is a common trick in the DIY community. It makes the paint thinner, prevents spray gun clogging, and saves the cost of buying specialized thinners (around a dozen dollars). However, in practice, it comes with a host of issues: the dried paint turns dull, metallic paint loses its shine entirely; the finish becomes uneven, resembling orange peel texture; and the lingering gasoline smell can last for months. More critically, it harms the car—gasoline can seep into plastic bumpers, causing brittleness and cracks. Last week, my neighbor used gasoline for touch-up paint, and the new paint layer peeled off entirely within three months. The auto shop said the entire filler must be stripped and redone.

[DiJaxson]

The core principle of adding gasoline to paint is 'like dissolves like.' The organic solvents in paint are similar in composition to gasoline, which can reduce viscosity and improve fluidity when added. This method is commonly used in the renovation of older vehicles, especially when repairing cast iron engines, as gasoline can penetrate rust. However, modern cars are made of composite materials, and gasoline can corrode plastic lamp covers, rubber seals, and even cause electrical short circuits. Experienced technicians prefer to spend an extra half-hour stirring specialized thinners, as paint mixed with gasoline tends to crack and peel within two years at most, leading to higher rework costs.