Petroleum jelly is a semi-solid, waxy paste composed of a complex mixture of mineral oils and waxes. This common household product, often used for skin protection, is a refined byproduct of the petroleum distillation process. While it is not easily ignitable at room temperature, petroleum jelly is combustible and will sustain a flame if exposed to enough heat.
The Direct Answer: Is Petroleum Jelly Flammable?
Petroleum jelly is classified as a combustible material rather than a flammable one because it requires significant and sustained heat to ignite. This distinction is based on its high flashpoint, which is the lowest temperature at which a substance produces enough ignitable vapor to start a fire. Because petroleum jelly is composed of heavy hydrocarbons, it naturally possesses a high flashpoint.
This flashpoint typically ranges between 182 degrees Celsius and 221 degrees Celsius (360°F to 430°F). A simple spark or a brief touch from a match will not cause the jelly to catch fire because the heat dissipates too quickly to reach this temperature threshold. Combustion can only occur after the jelly has been heated enough to melt and then vaporize the oils, as it is the hydrocarbon vapors, not the semi-solid substance itself, that actually burn.
How Petroleum Jelly Functions as a Fire Starter
The high flashpoint explains why petroleum jelly is not used as an initial ignition source, but rather as an effective fire fuel extender. When used for fire starting, the jelly is combined with a wicking material, such as cotton balls or dryer lint. This combination provides the sustained heat and surface area necessary for the hydrocarbon vapors to ignite.
The initial flame is applied to the dry fibers of the wick, which ignite quickly and melt the surrounding jelly. As the petroleum jelly liquefies, it is drawn into the fibers, saturating the wick and turning it into a slow-burning, candle-like fuel source. A plain cotton ball may burn for only about 30 seconds, but one saturated with petroleum jelly can maintain a flame for four minutes or more. This extended burn time provides a steady, reliable flame needed to ignite kindling and larger pieces of wood, even in damp conditions.
Safe Usage and Storage Practices
Petroleum jelly should be stored and handled with an awareness of its combustible nature. Containers should always be kept away from open flames, pilot lights, gas stoves, and other high-heat sources. The product has a relatively low melting point, sometimes as low as 40 degrees Celsius, so storing it in hot locations like a car dashboard or near a window can cause it to liquefy.
The greatest risk of accidental ignition comes from applying the jelly too close to a heat source, such as a candle or gas burner, where the heat can cause the substance to melt and vaporize. If petroleum jelly catches fire, it burns with a bright yellow-orange flame and produces thick, black, sooty smoke, which can contain toxic fumes. Water should not be used to extinguish a larger fire involving the jelly, as it can cause the burning oil to spread. Instead, use a fire extinguisher rated for chemical fires or a non-flammable cover to smother the flames.