Gunpowder, used in firearms and pyrotechnics, is significantly affected by moisture. When gunpowder gets wet, its effectiveness and safety are compromised due to immediate functional changes and underlying chemical and physical processes.
Loss of Ignitability
When gunpowder encounters water, its ability to ignite and propel is compromised. Wet gunpowder, whether black powder or smokeless, loses its capacity to ignite or burns inefficiently. Water interferes with the rapid combustion needed for a controlled burn.
For black powder, water can dissolve key components, disrupting the intimate mixture required for a swift reaction. Smokeless powder relies on a precise burn rate to generate the rapid gas expansion needed for propulsion. Water interferes with this delicate process, making ignition unreliable and the burning erratic.
The Chemical and Physical Reasons
The loss of ignitability stems from the distinct chemical compositions and physical structures of black powder and smokeless powder. Black powder, an older propellant, consists of a mixture of potassium nitrate, charcoal, and sulfur. Potassium nitrate acts as an oxidizer, supplying oxygen for combustion, while charcoal and sulfur serve as fuels.
Water’s strong polarity readily dissolves the highly soluble potassium nitrate. This separation of the oxidizer from the fuels prevents rapid, self-sustaining combustion. Water also absorbs heat, preventing the mixture from reaching ignition temperature.
Modern smokeless powder primarily uses nitrocellulose, often combined with nitroglycerin in double-base powders, along with stabilizers and other additives. These powders are manufactured as grains with specific shapes and porosities designed for a controlled burn rate. Water can penetrate the porous structure of these grains, absorbing the heat produced during the initial stages of combustion. This interference disrupts the consistent burning process that relies on rapid and controlled gas expansion. The integrity of the grain structure is also crucial for consistent burn rates, and water can compromise this physical characteristic.
Drying and Reusing Wet Gunpowder
Drying wet gunpowder for reuse is not recommended due to unpredictable performance and safety concerns. For black powder, drying often leads to the recrystallization of potassium nitrate. This recrystallized potassium nitrate can form larger, less reactive crystals, which results in a less powerful or even inert product. The intimate mixture necessary for efficient combustion is not easily restored simply by drying.
Attempting to dry and reuse smokeless powder also carries significant risks. Water exposure can alter the burn rate of smokeless powder in unpredictable ways. A change in burn rate can lead to dangerous pressure spikes within a firearm, potentially causing damage to the weapon or injury to the user. Conversely, the powder might burn too slowly, resulting in a “squib load” where the projectile does not exit the barrel. The loss of consistent performance makes dried gunpowder unsuitable for reliable use.
Safety of Wet Gunpowder
Even if wet gunpowder loses its immediate ignitability, it is not entirely harmless and still requires careful handling and proper disposal. The immediate risk of an explosion is significantly reduced when gunpowder is wet. However, wet conditions can accelerate the chemical decomposition of gunpowder, particularly smokeless powder. This decomposition can lead to the formation of unstable byproducts over time, posing a potential hazard during storage.
The organic components present in both types of gunpowder can also encourage the growth of mold or mildew in damp environments. If water within the gunpowder freezes, it can expand and physically break down the granular structure of the powder. This further alters the powder’s properties, making it unpredictable if it were to dry out later. Therefore, wet gunpowder should be handled with caution and disposed of appropriately rather than attempting to dry or use it.