Napalm is an incendiary material designed to be a highly effective weaponized mixture of a volatile fuel and a thickening agent. It is not a single chemical substance but rather a class of compounds engineered to burn with intense, localized heat over a sustained period. The primary purpose of the gelling agent is to transform a thin, easily dispersed liquid fuel, such as gasoline, into a sticky, viscous substance. This structural change gives napalm its notorious ability to adhere to surfaces and resist typical extinguishing methods.
The Chemical Makeup of Napalm
Napalm’s composition has evolved since its invention in 1942, but it has always consisted of a fuel base and a specific gelling agent. The original formulation, sometimes called Napalm-A, was created by combining a petroleum fuel with co-precipitated aluminum salts of naphthenic and palmitic acids. The name “napalm” is a portmanteau derived from these two organic acids. This powder, when mixed with gasoline, forms a gelatinous substance much thicker than the original liquid fuel.
A more modern variant, often referred to as Napalm-B, utilizes a polymeric thickener like polystyrene. This contemporary mixture often contains a blend of gasoline, benzene, and polystyrene. Polystyrene is a synthetic polymer that, when dissolved in the fuel, creates a more stable and sticky gel compared to the original formulation. The function of this thickener is to increase the mixture’s viscosity, allowing it to be propelled cohesively and making it stick firmly to targets.
The change in physical state fundamentally alters the fuel’s behavior during combustion. By increasing the viscosity, the gelling agent ensures the fuel does not flow away or splash off a surface, maximizing contact time for the burn. While the fuel base determines the temperature and energy released, the thickener controls the physical properties, particularly persistence and adherence.
How Napalm Sustains Combustion
The unique combustion properties of napalm stem directly from the physical characteristics imparted by the gelling agent. Once ignited, the viscous gel adheres strongly to any surface, preventing the burning material from being easily dislodged. This adhesion keeps the heat source localized and in direct contact with the target material for an extended period.
The gel structure also acts as an insulator, which sustains the high burning temperature. The outer layer of the gel combusts, shielding the material underneath from external cooling influences. This insulation helps maintain the fuel’s temperature above its ignition point, ensuring a slow, continuous burn rather than a rapid flare-up.
Napalm burns at temperatures typically ranging from 800 to 1,200 degrees Celsius (1,470 to 2,190 degrees Fahrenheit). This intense heat is sustained because the viscous structure slows the rate at which volatile fuel vapors are released and consumed. The result is a prolonged reaction that can last for several minutes, with modern Napalm-B formulations burning for up to 10 minutes.
The Interaction Between Napalm and Water
The question of whether napalm burns underwater touches upon the fundamental requirements for combustion. True fire requires a fuel source, heat, and an oxidizer, typically oxygen from the air. Since water contains virtually no free oxygen to support the chemical reaction of fire, napalm cannot sustain a flame completely submerged.
However, napalm’s physical properties make brief submergence and attempts at extinguishing it with water largely ineffective. The primary fuel component is less dense than water, meaning burning napalm will float to the surface. If dropped into water, it will spread out and continue to burn atop the surface, where it can access atmospheric oxygen.
The insulating gel structure plays a role when napalm is adhered to a submerged or partially submerged object. The intense heat of the burning gel, reaching over 1,000 degrees Celsius, causes surrounding water to flash-vaporize immediately upon contact. This rapid vaporization creates a temporary steam barrier that pushes the liquid water away from the burning surface. The steam layer prevents the water from effectively cooling the fuel or smothering the flame.
To extinguish a napalm fire with water, the material must be cooled significantly below its combustion temperature, or it must be completely starved of oxygen for a prolonged period. This generally requires deep, prolonged submergence until the material’s internal heat is fully dissipated. Superficial water application or brief dips are ineffective, as the buoyancy of the fuel and the insulating nature of the gel allow combustion to persist as long as oxygen remains available.